Sociotechnical Complexities Associated with the Development of
Building Integrated Photovoltaic Faeade Systems
by
Jorge Moreno
:7:
Ingeniero Civil Electricista,
Magister en Ciencias de la Ingenieria,
Pontificia Universidad Catolica de Chile, 2004
SUBMITTED TO THE SYSTEM DESIGN AND MANAGEMENT PROGRAM IN
PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF
Master of Science in Engineering and Management
at the
Massachusetts Institute of Technology
Dc mber 2012
u
C 2012 Jorge Moreno. All rigits reserved.
The authors hereby grant to MIT permission to reproduce and to distribute publicly paper
and electronic copies of this thesis document in whole or in part in any medium now
known or hereafter created
Signatures of A uthors ...........................................
Engineering Systems
. ...... ....................................................
Jorge Moreno
vision and Sloan School of Management
December 3, 2012
/')
C ertified by.....................................
.........
. .. ........................
James M. Utterback, Thesis Supervisor
David J.
rathjr (1959) Professor of Management and Innovation and
Professor of Engineering Systems MIT Sloan School of Management
A ccepted by............................
.... .....
..............
................
...
Patrick C. Hale
Director of System Design and Management Program
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2
Sociotechnical Complexities Associated with the Development of
Building Integrated Photovoltaic Faeade Systems
by
Jorge Moreno
Submitted at the System Design and Management Program on December 3, 2012 in Partial
Fulfillment of the Requirements for the Degree of Master of Science in Engineering and
Management
Abstract
Significant opportunities to improve the energy use in buildings open remarkable
possibilities for innovation over the next two decades. Particularly in the United States,
41% of primary energy consumption in 2010 went into buildings.
This work has applied a broad perspective that combines management, technology, and
social sciences to analyze the development and integration challenges of emerging
Building Integrated Photovoltaic (BIPV) systems that would likely be integrated into
building fagades as part of a portfolio of alternatives that might contribute to the
development of zero-energy buildings.
The analysis contributes to identify some sociotechnical complexities associated with the
development
of BIPV systems. In addition, it characterizes different products'
architectures based on their technical performance, technical complexity, perceived
complexity, and exposure to subjective judgment. It shows that the resolution of the
friction between the aesthetic and the electricity generation function is one of the earlystage design decisions that may have significant influence on the adoption of the system.
Thesis Supervisor: James M. Utterback
David J. McGrath jr (1959) Professor of Management and Innovation and Professor of
Engineering Systems
3
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4
Acknowledgements
When I reflect about the two years I spent at MIT, I would like to express my sincere
appreciation to the people that made this experience possible. First and foremost, I would
like to thank my wife, Macarena, for her support and comprehension. Next, I would like to
thank my parents and my sister. Undoubtedly, without their unconditional love, support
and encouragement, I would not be where I am today.
Next, I would like to thank Dr. James Utterback, my advisor; the Director of the SDM
Program, Mr. Pat Hale, the SDM staff, and my classmates. It has been an honor to be part
of this special group of people.
In addition, I would like to thank the TechBridge Program at the Fraunhofer Center for
Sustainable Energy Systems. Jeff McAulay and Peter Klint for their support in my research
associated with this thesis. Finally, I would like to thank Conicyt and the Becas Chile
Program who supported my graduate studies at MIT.
5
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6
Contents
7
Contents ................................................................................................................................
List of Figures.......................................................................................................................9
List of Tables ......................................................................................................................
13
Chapter 1 - Introduction & Objective..........................................................................
15
Introduction and M otivation ...............................................................................
15
1.1.1 W hat technology does this thesis study?......................................................
18
1.1.2 What managem ent aspects are involved in this work? .................................
19
1.1.3 How does this research relate to social sciences?...........................................
19
The Problem ............................................................................................................
23
Chapter 2 - Explanation of the Key Concepts ..........................................................
25
2.1
Dynam ics of Innovation......................................................................................
25
2.2
Radical Innovation and Meaning ........................................................................
28
2.3
Innovation Challenges in the Construction Industry...........................................
32
2.4
System Architecture Principles...............................................................................33
1.1
1.2
Chapter 3 - BIPV Faeade Artifacts - Use Context, Needs and Objectives..............38
3.1
The System of Interest ............................................................................................
3.2
Why the System is Built. Need Opportunity...........................................................39
38
3.2.1 Near-Zero Energy Buildings..........................................................................
40
3.2.2 Building Integrated Photovoltaic (BIPV) ......................................................
44
3.2.3 BIPV Fagade System s....................................................................................
7
50
3.3
Fagade Photovoltaic Artifacts (FPVAs).............................................................53
3.3.1 What the system accom plished ..........................................................................
53
3.3.2 Types of PV and FPV A .................................................................................
55
Stakeh o lders ............................................................................................................
61
3 .4
Chapter 4 - Faeade Building Integrated Photovoltaics: System Architecture Analysis
..... 69
........................................
.....
..............................................
System Architecture Analysis - Artifact Level ......................................................
4.1
72
4.1.1 Opaque BIPV Fagade System s ..........................................................................
73
4.1.2 Semi-transparent System s .............................................................................
77
4.1.3 T ransparent System s ..........................................................................................
88
4.1.4 Summary of the Systems Architecture Analysis...........................................90
4.2
Implication for Market Adoption: Dominant Design ........................................
Chapter 5 - Conclusions........................
Chapter 6 - Bibliography..............................
8
....................
.......................
93
97
101
List of Figures
Figure 1: Mural used in a General Electric exhibit (New York World's Fair, 1939).....22
Figure 2: Historical example of electricity use as a source of environmentally friendly
product differentiator .......................................................................................................
23
Figure 3: Characterization of technological innovation (from Henderson and Clark) ........ 25
Figure 4: Integration of PV on the two extremes of the electricity market value chain ...... 30
Figure 5: The strategy of design-driven innovation (adapted from Verganti 2009, p. 5 and
7 5) ........................................................................................................................................
31
Figure 6: Integration of PV. Large Scale (left), Building Integrated (Right) .................
31
Figure 7: System of Interest in Context ..........................................................................
38
Figure 8: Connection between buildings and energy grids (from Sartori 2012).............43
Figure 9: N ear-Zero Energy Buildings ............................................................................
44
Figure 10: Types of Building Integrated Photovoltaic Systems (EnergyGlass).............46
Figure 11: Comparative total insolation over a year for all angles of tilt from horizontal and
orientation -
building located in Freiburg, Germany (Roberts and Guariento 2005, 34)..49
Figure 12: Fagade functional requirements (Knaack, et al. 2007, 36)............................51
Figure 13: Fagade functional requirements and concept.................................................52
Figure 14: Functional representation of the concept (Knaack, et al. 2007, 130) (left).
Simplified flow chart of the design of the system (right) ..............................................
53
Figure 15: Influence of stakeholders in the Product Architecture (adapted from Crawley
2 0 11) ....................................................................................................................................
9
54
Figure 16: Evolution of best research-cell efficiencies (NREL)......................................56
Figure 17: Median installed price of customer-owned PV Systems s10kW. (From Seel,
B arbose and Wiser 2012).................................................................................................
57
Figure 18: Different types of Fagade BIPV Systems......................................................58
Figure 19: Different types of Fagade BIPV Systems (examples) ...................................
58
Figure 20: Comparison of fagade photovoltaic artifacts (efficiency vs transparency)........59
Figure 21: BIPV product market strategy ........................................................................
61
Figure 22: Interactions in complex engineering systems (From Bartolomei 2007)........62
Figure 23: Stakeholders of a BIPV project (adapted from Crawley)...............................63
Figure 24: Prioritizing stakeholders (adapted from Crawley).........................................64
Figure 25: Stakeholder value chain of a BIPV Fagade Project........................................66
Figure 26: Decomposition into separate functional elements (left) and layered elements
(right)
(Knaack, 2007 p. 56)....................................................................
69
Figure 27: Specific annual energy demand of an office building in central Europe -double
glazing (K naack, et al. 2007, 70).....................................................................................
70
Figure 28: Specific annual energy demand of an office building in central Europe -triple
glazing (K naack, et al. 2007, 70).....................................................................................
70
Figure 29: Specific annual energy demand of an office building in central Europe -triple
glazing & external sun protection (Knaack, et al. 2007, 70)...........................................71
Figure 30: Opaque BIPV Fagade Systems - Interface analysis..................74
Figure 31: Opaque BIPV Fagade Systems -
Map of Functional Requirements and Design
Param eters ............................................................................................................................
10
76
Figure 32: Semitransparent BIPV Fagade Systems Figure 33: Spaced Crystalline Panel -
Interface analysis ............
79
Map of Functional Requirements and Design
P aram eters ............................................................................................................................
80
Figure 34: Spaced Crystalline BIPV Panel - Source: Renewable energy focus (left).
E nergyG lass (Right).............................................................................................................81
Figure 35: Solar reflector concentrator concept. Pythagoras Solar (Left), Tropiglas (Right)
..............................................................................................................................................
82
Figure 36: Solar reflector concentrator with crystalline cells. Source: Pythagoras Solar
(left), Invisergy (right) .....................................................................................................
84
Figure 37: Qualitative comparison of the system's complexity .....................................
84
Figure 38: Solar reflector concentrator with crystalline cells -
Map of Functional
Requirem ents and Design Param eters.............................................................................
Figure 39: Semi-transparent BIPV Panel -
86
Map of Functional Requirements and Design
P aram eters ............................................................................................................................
87
Figure 40: Application of Semi-transparent BIPV Panel (Source: Schott Solar)............88
Figure 41: Application of Semi-transparent BIPV panels by degree of transparency: 5%
(left), 15% (center), 25% (right). (Source: Schico Fagade Modules) ...............
88
Figure 42: Transparent BIPV Fagade Systems -
89
Figure 43: Transparent Panel -
Interface analysis ..............................
Map of Functional Requirements and Design Parameters
..............................................................................................................................................
90
Figure 44: Energy transformation performance and system complexity-comparison
betw een different concepts...............................................................................................
92
Figure 45: Energy transformation performance, system complexity, and perceived
complexity-comparison between different concepts....................................................93
11
12
List of Tables
Table 1: Significant Characteristics in the Three Phases of Industrial Innovation (adapted
from U tterback 1996 p. 94-95) .......................................................................................
27
Table 2: Specific Activities for Implementation by Type of Innovation. (From Slaughter
19 9 8) ....................................................................................................................................
33
Table 3: The N eed Opportunity .....................................................................................
40
Table 4: Advantages and disadvantages of different types of PV systems.....................45
13
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14
Chapter 1 - Introduction & Objective
1.1
Introduction and Motivation
Energy consumption will likely triple by the end of this century. Innovation within the
energy industry is required so as to decrease greenhouse emissions, which would increase
even if clean fossil fuel technologies were employed (Beck 2002). Historically, energy has
been largely supplied by fossil fuels (Koonin and Gopstein 2011). More recently, in 2009,
88% of the primary energy consumption was supplied by fossil fuels (BP p.l.c. 2010).
The International Energy Agency states that not only do 1.3 billion people not have access
to electricity, but also there still exist tremendous disparities in energy consumption (IEA
2011, Chapter 13). Similarly, Vaclav Smil emphasizes that the majority of humanity, in
particular in developing countries, will need to consume more energy in order to increase
its quality of life; in contrast, developed countries, in particular the U.S., should reduce
their energy use so as to contribute to a more sustainable society (Vaclav 2011). According
to Smil, this friction between energy supply and consumption has led to an unrealistic
appraisal related to the role of renewable energy and an impetuous and unavoidable shift
from a dominant source of energy to a new supply structure. Historically, energy
transitions have taken approximately five decades (Koonin and Gopstein 2011).
Nevertheless, according to Professor Richard Lester, different surprises have recently
affected the world of energy: first, the 2010 oil spill in the Gulf of Mexico; second, the
political instability in Middle East and North Africa; third, the recent transformation of the
gas supply in the U.S.; and lastly, the events at Fukushima Daiichi Nuclear Plant (R. Lester
2011). Lester commented: "each one of these surprises on its own is a game changer. Since
in the world of energy not only are there surprises, but also everything is connected, we
have to consider them altogether, and what is more, we have to be prepared for more
surprises in the future." Furthermore, in his book Unlocking the Energy Innovation, Lester
emphasizes that the forthcoming energy transition will not yield to a single solution.
Instead, it will require a diversified portfolio of options that will need to be refined over
15
time (Lester and Hart 2012, 25). Lester also argues that a major change in the current
energy supply structure will likely take decades.
However, disruption can also occur in the energy industry. Rapid technological paradigm
shifts have been associated either with severe accidents or disruptions in the supply of
fossil fuels. On the one hand, after Three Mile Island and Chernobyl accidents,
governments denied support to the construction of new nuclear power plants. Similarly, the
willingness to build new nuclear power plants has significantly decreased since the
Fukushima accident, which has also produced significant changes in the nuclear industry in
different countries. On the other hand, the availability of fossil fuel resources has produced
paradigm shifts in energy markets. For example, an energy transformation phenomenon is
currently ongoing in the U.S. with the exploitation of shale gas.
According to Harvey Brooks (Brooks 1980), from 1900 to 1980, technological progress
has been more focused on labor or time savings than on material and energy savings. This
is because during the
2 0
th
century the cost of labor increased faster than that of energy or
materials. Therefore, the major technological innovation effort was directed to reduce costs
on the most expensive input.
In the
2 1 st
century, in order to provide universal access to electricity, the widespread
adoption of new technologies and renewable sources of generation is required to limit the
dependency on fossil fuels, reduce the depletion of natural resources, and confine the
accumulation of greenhouse gases in the atmosphere. However, this adoption implies
broad challenges. Undoubtedly, there are technical, commercial, and institutional barriers,
especially related to the adoption of new technologies in highly regulated markets, where
the economies of scale and the stock of historical developments significantly influence the
market behavior (Weiss and Bonvillian 2011).
The adoption of renewables has other difficulties as well. Customers cannot differentiate
among the sources of electricity when it is consumed, and abundant renewable energy
resources are generally both highly intermittent and far from demand centers. Furthermore,
large-scale adoption of renewable energy sources not only relies on the development of
both large scale and distributed sources of generation, but also depends on the construction
16
of power lines across different regions and the development of energy storage systems.
The latter factor makes the integration of renewables even more difficult.
In order to support an eventual energy transition, we require innovation in different areas.
James Utterback defined the dynamic of innovation by conceptualizing three market
phases: Fluid, Transitional, and Specific phases. Because new enterprises and technologies
compete in a Fluid Phase market, and the characteristics of incumbent companies and
technologies that compete in the energy industry - which is in a Specific Phase - are
different, many frictions arise that limit innovation (J. Utterback 1996, 79-102) (Utterback
and Kim 1986).
In addition, Utterback defined the concept of dominant design, the emergence of which
depends on different factors (J. Utterback 1996, 23-57). Once the dominant design emerges
in a determined market, it is difficult for other technologies to compete based on the same
performance metrics. In highly regulated markets, innovation and product success have
been historically forced mainly by new environmental and safety requirements (Allen, et
al. 1978). By introducing regulatory changes and establishing new criteria for defining a
successful product or process, governments force innovation in sectors that have been
overlooked by market forces (Allen, et al. 1978) (Winner 1980) (Porter 1998, 47).
In the United States, 41% of primary energy consumption in 2010 went into buildings.
This consumption represents 7% of the global primary energy consumption (DOE 2011,
Chapter 1). The building and energy sectors have a striking legacy embedded in different
factors that limit innovation (Weiss and Bonvillian 2011). However, there are significant
opportunities to improve the efficiency in energy use in buildings. For instance, according
to the National Research Council (NRC), over the next 25 years, the U.S. could cut its
energy use in buildings by almost 30% compared to a business-as-usual scenario (National
Research Council 2009). The NRC states that this energy cut would likely be achieved
without any changes in technology.
This need for improvement in buildings' energy consumption opens a remarkable
opportunity over the next two decades. Because approximately 75% of the built
environment in the U.S. would be either new or renovated by 2035 (Architecture 2030),
17
and all new buildings in the E.U. will need to comply with near-zero energy consumption
standards by 2020 (European Parliament 2010), two opportunities are emerging: 1) to
increase the buildings' energy performance, and 2) to supply energy locally by using
distributed sources of clean energy technologies that could be integrated into the building
architecture.
The right solution will require reviewing and improving a combination of systems that are
currently in use in building. For example, energy performance of buildings can be
improved by reviewing 1) domestic hot water systems, 2) miscellaneous equipment used in
the building, 3) building fagades, 4) lighting systems, 5) heating systems, 6) cooling
systems, 7) energy management systems, and so forth. Similarly, renewable energy can be
locally supplied by installing 1) photovoltaic generation systems, 2) combined heat and
power solar systems, 3) wind generation systems, and so forth.
Inspired by the vision of the System Design and Management Program, I applied a systems
thinking perspective that combines management, technology, and social sciences to
analyze the development and integration challenges of an emerging, novel product. In the
following three sub-sections, I explain how these aspects are related in this work.
1.1.1
What technology does this thesis study?
The technology analyzed in this work intends to power energy needs in buildings by
supplying environmentally friendly electricity using a system integrated with the building
envelope. The system shall convert a ubiquitous source of energy (solar energy) into
electricity. In addition, the system should provide other benefits such as decreasing the
heating and cooling load in the building, leveraging the building's aesthetic, and, if
possible, other tangible benefits. The research focuses on a concept known as Building
Integrated Photovoltaic (BIPV) systems, in particular, those that will likely be integrated
into building fagades.
According to Pike Research estimates, BIPV is one of the fastest-growing segments in the
solar industry. Up to 4.6 GW of installations would likely be constructed by 2017 (Pike
Research 2012).
18
BIPV systems can be developed using different components and architectures. Currently
there are several innovational endeavors in both the component and the product
architectural dimensions. This diversity and lack of a dominant architecture characterizes
an industry in a Fluid Phase (J. Utterback, 94).
In addition, if the system boundaries are expanded, we shall consider the BIPV system as
part of a larger system in terms of the physical structure in which it will be integrated (i.e.,
building architecture) and the electrical system in which it could be interconnected (i.e., the
building's electric network, a local micro-grid, and even the electric interconnected system
through the utility's distribution network).
1.1.2
What management aspects are involved in this work?
This work examines numerous management components. The key elements that influence
the architecture of BIPV systems include the customer needs, the competitive environment,
the market regulation, the competence of the supply chain, building codes, the channel to
market, and even the interactions between the BIPV system and the building in which it
will be integrated.
Numerous early-stage startups are currently developing BIPV fagade systems. This work
aims to support the planning and commercialization of BIPV fagade systems. Some
management aspects include the analysis of the strategy to create and capture value.
Therefore, this work reviews the identification of customer needs, the development of the
concept, and the analysis of different product architectures in order to support the
understanding of the complexities behind different concepts.
1.1.3
How does this research relate to social sciences?
Alberto Alessi, CEO of the Italian manufacturer of household items Alessi, believes that
"we are surrounded by a world of anonymous products, of boring objects, most often
lacking any emotion and poesy" (Verganti 2009, 47). This comment firmly represents how
people perceive electricity during the last decades: it is just a commodity.
Large power plants concentrate the environmental and visual impact in a specific area,
affecting not only the environment, but also the people who live in the surroundings. In
19
some instances, it would be hard to define the affected parties because groups far from the
site might have an stake in its conservation - in some way these people are the users of the
site and the proposed industrial facility, but they are not the clients of the primary benefit
that the facility produces. This separation between clients and users challenges system
architects, who have to manage the friction between preferences that may not be
imperative for the utility agency and preferences of the public (as perceived by the system
architect); in particular, when these preferences strongly affect system design (Maier and
Rechtin 2009, 131-134).
In this context, we observe a growing phenomenon regarding the "Not in my Backyard"
(NIMBY) concern that stresses the development of all types of energy facilities around the
globe, even relatively large-scale renewable energy systems.
At the same time, we are observing the blurring of production and consumption in different
industries' (Brown 2011). This phenomenon means that, in some niche markets, the
consumers are the producers of their own goods. Regarding the energy sector, the blurring
of production and consumption can be associated with the concept known as distributed
generation, where small sources of generation are installed along the distribution network,
close to the customer. The extreme manifestation of this phenomenon would likely be
BIPV and the vision of near-zero energy buildings, where the source of generation will be
tightly integrated with the building space.
Why are social factors relevant in the technology innovation process? According to
Langdon Winner (1980), "in a societal context what matters is not technology itself, but
the social or economic system in which it is embedded." Utterback et al. (Utterback,
Vedin, et al. 2006, 5) indicate that the innovation process requires a deep knowledge of
user needs, technological opportunities, and product languages; the latter is particularly
important in systems that entail significant social interaction. Utterback et al. emphasize
that knowledge about languages is essential. However, system designers and managers do
not need to play the role of sociologists; rather, "they may anticipate hidden and emerging
1 For instance, this convergence has profoundly transformed the way we know the media:
using platforms such as Facebook and Twitter, we are the producers of our own media
content.
20
phenomena in the society, and talk about new, unexpressed, semantic needs of users...
designers observe the socio-cultural models and make proposals to affect the emerging
dynamics of socio-cultural models" (Utterback, Vedin, et al. 2006, 177). Similarly,
Clayton Christensen indicates that "marketers need to understand the jobs that arise in
customers' lives for which their product might be hired" (Christensen, Anthony, et al.
2007); likewise, Roberto Verganti defines "design-driven innovation as an innovation in
which the novelty of a message and of a design language prevails over the novelty of
functionality and technology" (Verganti 2003). Radical innovation of meaning emerges as
a vision of a feasible future; the market does not pull radical innovation of meaning
(Verganti 2003).
This social analysis can also be applied to electricity systems. David Nye in the book
Electrifying America states: "From the start, home electrification was not merely
utilitarian. The novelty of the new force encouraged experimentation, and people took
pleasure in festooning their homes and gardens with light, not in order to see better, but to
see their possessions anew" (Nye 1992, 245).
In this context, electricity has been firmly related with social meanings. The use of
electricity rapidly increased productivity in factories, restructured family life at home, and
transformed lifestyle and productivity in cities and farms. Nye indicates: "Electrification is
thus far more than the story of inventions and corporations; it involves a popular
absorption in the potentialities for personal and social transformation, being directly
related with wealth, power and privilege" (Nye 1992, 382).
Finally, Utterback argues: "the evidence shows that we are indeed coming (returning?)to
innovation inspired by design that truly delights the user" (Utterback, Vedin, et al. 2006,
227). As documented by Nye, in the beginning of the
2 0
th
century, the electricity delighted
communities in multiple dimensions, which is exemplified in Figure 1.
21
Figure 1: Mural used in a General Electric exhibit (New York World's Fair, 1939)2
Finally, electricity was also used as a marketing differentiator in some products. For
example, Figure 2 shows the case of biscuits baked by electricity produced by "whitecoal," 3 elaborated during the early development of hydroelectric power in Niagara Falls.
Image from:
http://digitalgallery.nypl.org/nypldigital/dgkeysearchdetail.cfm?struclD=1799783&imageI
D=1696292&k=0&print=small (Accessed September 2012)
3 At the beginning of the 2 0th century, hydroelectric power plants were known as "White
coal" energy, as they represented a new, environmentally friendly energy source. (Hughes
1987, 262-284).
2
22
4
Figure 2: Historical example of electricity use as a source of environmentally friendly product differentiator
1.2
The Problem
This work identifies some sociotechnical complexities related to the progress of various
novel building integrated photovoltaic systems that would likely be integrated into building
fagades as part of a portfolio of alternatives that might contribute to the development of
near-zero energy buildings. It addresses the identification of stakeholders' needs and the
high-level analysis of different system architectures in order to distinguish those concepts
with fewer complexities and consequently development frictions.
The problem is important because the building integrated photovoltaic market is in a fluid
phase of the dynamics of innovation; therefore, there is no dominant design. Even market
needs are not clearly defined, and there are some regulated markets that have both set
future goals for near-zero energy building architectures and segmented tariff schemes that
incentivize the adoption of solar generation in buildings.
Image from: http://www.atticpaper.com/proddetail.php?prod=1903-triscuit-biscuit-twosided-ad (Accessed September 2012)
23
4
In this context, this analysis contributes to characterize different products' architectures
based on their technical performance, technical complexity, perceived complexity, and
exposure to subjective judgments.
I have shown that fagade building integrated photovoltaic systems are highly exposed to
subjective judgments that directly compromise the technical performance function of the
system, in particular in those systems attempting to provide multiple functions through
layered elements that allow both electricity generation and visibility with the intent to
diminish reliance of external sources of energy and aesthetically supplement custom
curtain walls.
The essence of this study shows how to apply systems architecture principles to evaluate
different novel building integrated photovoltaic concepts, illustrating both technical and
perceived complexities that could constrain further developments when technologies are
attempting to establish their commercial viability.
Chapter 2 summarizes the main concepts associated with innovation and systems
architecting in the construction industry, such as the dynamic of innovation, the relation
between radical innovation and meaning, the innovation challenges in the construction
industry and the ten principles that I consider relevant when architecting systems.
Chapter 3 introduces the concept of building integrated photovoltaic systems and its use in
the context of near-zero energy buildings. In addition, the chapter presents the basic
physics behind the operation of the operation of photovoltaic in buildings, the
stakeholders' needs and the relation between stakeholders, defining the high-level
functions for building integrated photovoltaic instruments (artifacts).
A systems architecture analysis of building fagades and building integrated photovoltaic
concepts that can be utilized in building fagade is presented in Chapter 4. The analysis
considers three families of products that have been identified and entails the high-level
decomposition in functional requirements and design parameters so as to compare the
complexities behind different systems architectures. Finally, Chapter 5 offers conclusions.
24
Chapter 2 - Explanation of the Key Concepts
2.1
Dynamics of Innovation
System design involves knowledge regarding the conceptualization of ideas and its
synthesis into components, and the arrangement of elements of form and functions among
the interacting elements and with the surrounding context -
i.e., system architecture
(Crawley 201 1b). Henderson and Clark synthesized innovation in system design by
distinguishing four conceptual types of innovation (Figure 3), classified along two
dimensions depending on the degree of change in the system's components and the
linkages between the system's components (Henderson and Clark 1990).
Architectural innovation involves the arrangement of existing components in a new way so
that the emerging function of the system as a whole is more valuable than the sum of the
functions of each of the components taken separately. Radical innovation synthesizes
novel design concepts and components in a new system architecture. The integration of
photovoltaic systems into the building fagade can be classified as radical innovation in the
building industry -
it involves new materials and new system linkages that affect different
stakeholders along the value chain: component manufacturers, building developers,
building contractors, building owners, and building users.
Core Concepts and Components
Reinforced
Changed
CO
oo ~
CU
Incremental
Innovation
Modular
Innovation
0.
aD
Architectural
Radical
Innovation
Innovation
)
CU
Figure 3: Characterization of technological innovation (from Henderson and Clark)
25
Utterback indicates that the rate of product and process innovation and the characteristics
of the market over time differ along three phases in the dynamic of innovation: Fluid
Phase, Transitional Phase and Specific Phase, described in Table 1 (J. Utterback 1996, 79102). When products that involve radical innovation are emerging (i.e., Fluid Phase), there
is substantial technical uncertainty not only related with the system's components, but also
with the system architecture; consequently, experimentation is a fundamental process that
needs to be developed in conjunction with lead users (Thomke 2003, 89-123 and 241-272).
In addition, during the fluid phase of innovation, commercial risk is high because
customers' needs are not clearly understood, the product development entails both
significant
technical
risks
and development
time, the competitive
environment
continuously evolves, and system benefits and cost are not well defined. Novel clean-tech
solutions that entail high technological risk but relatively low capital investment are
typically financed by Venture Capital. However, the development of these technologies
frequently face funding gaps to scale while testing commercial viability, i.e., when they
intend to move from pre-commercial testing to large-scale deployment (Ghosh and Nanda
2010).
As an emerging product evolves and the market increases its adoption, a new technological
paradigm will likely emerge (Dosi 1982) (Geels and Schot 2007), which is generally
associated with a dominant design that reflects the adoption of a dominant system
architecture concept (J. Utterback 1996, 23-55). The emergence of a dominant design is the
result of the interaction between technical, socio-cultural, and scientific aspects, as well as
political and market choices at any particular time (J. Utterback 1996, 26) (F. W. Geels
2004).
26
Table 1: Significant Characteristics in the Three Phases of Industrial Innovation (adapted from Utterback 1996 p.
94-95)
Fluid Phase
Transitional Phase
Specific Phase
Innovation
Frequent major product
changes
Major process changes
required by rising demand
Incremental for product and
cumulative improvements
in productivity and quality
Source of Innovation
Industry pioneers; product
users
Manufacturers; users
Often suppliers
Products
Diverse design, often
customized
At least one product design,
stable enough to have
significant production
volume
Mostly undifferentiated,
standard products
Production Process
Flexible and inefficient,
major changes easily
accommodated
Becoming more rigid, with
changes occurring in major
steps
Efficient, capital intensive,
and rigid; cost of change
high
R&D
Focus unspecified because
of high degree of technical
uncertainty
Focus on specific product
features once dominant
design emerges
Focus on incremental
product technologies;
emphasis on process
technology
Plant
Small-scale, located near
user or source of innovation
General-purpose with
specialized sections
Large-scale, highly specific
to particular products
Cost of Process Change
Low
Moderate
High
Competitors
Few, but growing in
numbers with widely
fluctuating market shares
Many, but declining in
numbers after the
emergence of dominant
design
Few, classic oligopoly with
stable market shares
Basis of Competition
Functional product
performance
Product variation; fitness
for use
Price
Organizational Control
Informal and
entrepreneurial
Through project and task
groups
Structure, rules, and goals
Vulnerabilities of
Industry Leaders
To imitators, and patent
challenges; to successful
product breakthroughs
To more efficient and
higher-quality producers
To technological
innovations that present
superior product substitutes
Understanding and recognition of needs is imperative in any type of innovation. New
products must perform along several dimensions; consequently, the new technology must
excel the old on at least one performance metric to survive (Utterback and Kim 1986).
27
Disruptive technologies usually have lower performance metrics traditional market -
as valued in the
but have higher ancillary characteristics (Christensen 2011, xviii).
Furthermore, Utterback and Acee expanded the concept of disruptive technologies to
systems that, besides their ancillary characteristics, can have either higher or lower cost
and higher or lower traditional performance (Utterback and Acee 2005). In either case,
rather than adapt customer needs to match the performance of a new technology, the
introduction of novel technologies will likely be more successful in niche markets where
the performance metrics of the technology clearly match the customer needs (Christensen
2011, 220-221).
By establishing new criteria for defining a successful product or process, governments
force innovation in sectors that have been overlooked by market forces (Allen, et al. 1978)
(Winner 1980). Recently, innovation in the energy industry has been introduced by
utilizing a diversified set of regulatory instruments. Innovation policies can be classified
into technology push and market pull policies (Anadon and Holden 2009). Types of
technology push policies are federal ERD&D funding, public-private partnerships for
demonstration projects, international cooperation agreements in ERD&D, prizes and so
forth. On the other hand, known technology pull policies are portfolio standards,
performance standards, deployment incentives (direct expenditures, tax-related subsidies,
loan guarantees), and climate policies such as cap-and-trade and carbon tax.
2.2
Radical Innovation and Meaning
The ancient Greek philosophers identified four pursuits individually necessary and
collectively sufficient for the development of society: 1) the pursuit of truth, which is the
scientific and technological function of society, 2) the pursuit of plenty, which is the
economic function of society, 3) the pursuit of the good, which is the ethical-moral
function of society, and 4) the pursuit of beauty, which is the aesthetic function of society
(Ackoff 1981, 38-42). Ackoff indicates: "the aesthetic function is to inspire, to create
visions of the better and give us the courage to pursue it... but inspiration and aspiration go
hand in hand."
28
Traditionally, radical innovation has been associated with technological innovation. In
sociotechnical
systems -
technical
systems that compromise meaningful
social
participation and concerns - there is a permanent friction between facts and perceptions.
Generally, if the system sacrifices one foundation, e.g., technical performance, it can gain
another, the fulfillment of the user's needs and perceptions (Maier and Rechtin 2009, 127).
Perceptions are directly related with experiences and memory; consequently, the designer
should conceptualize artifacts that promote conditions by which happiness becomes
practicable (Pye 1995, 102). In that regard, Roberto Verganti proposed the strategy of
design-driven innovation -
i.e., radical change of meaning by proposing new experiences
to the user (Verganti 2009, 4), synthesizing knowledge of technology, language, and user's
needs (Utterback, Vedin, et al. 2006, 5). Meanings result from the interaction between user
and product (Verganti 2009, 35).
Any assessment of a disruptive technology over the established technology involves 1) an
understanding of its advantages in meeting user needs and 2) an assessment of the nature
of the industry that is likely to develop around a relevant product innovation (Cooper and
Smith 1992). Cooper and Smith found a tendency for institutions to use similar basic
approaches that were successful in the established industry to meet needs they had
previously served. They indicate that "the conventional wisdom" approach would be less
likely to succeed if a new technology enables different product concepts or ways of
competing. This can be related with innovation policies in renewable energy and the
emergence of design-driven innovation. On the one hand, there are renewable portfolio
standards and feed-in-tariff policies that are mostly oriented with a conventional form of
power plant development (Mendonca 2007). On the other hand, there are special feed-intariff schemes and policies that incentivize the installation of photovoltaic sources of
generation into buildings, forcing a paradigm shift in the integration of generation systems
(Figure 4). As the latter policies force a higher interaction between the user and the
electricity-generating system, design-driven innovation will likely emerge -
i.e., the
conceptualization of messages and meanings could become a strategic approach to satisfy
needs in distributed solar generation industry (Figure 5).
29
Generation
Transmission
Distribution
Consumption
Paradigm Shift
BIPV
Figure 4: Integration of PV on the two extremes of the electricity market value chain
Figure 6 illustrates the difference between a conventional solar power plant and a fagade
BIPV system. In this case, the form of the BIPV system reflects a symbolic concept, with a
strong sense of both aesthetic and harmony with the patterns of the natural surroundings
where it is immersed.
Although design driven innovation is emerging in different sectors, Verganti emphasizes
that products do not need to become more emotional or more symbolic; rather, he suggests
that products or services have meaning, and firms have always innovated in meaning
(Verganti 2009, 29).
30
Interaction Between Production and
Consumption Pulled by Policy Innovation
Changed
(FIT*, NZEB)
Unchanged
(RPS, FIT)
C
C
Q.
0O
Ground-mount
High Eff. PV
Plant
0
0W
C
Co
0
0
0
Ground-mount
PV Plant
0
Radical
Change
Incremental
Change
Meaning
Figure 5: The strategy of design-driven innovation (adapted from Verganti 2009, p. 5 and 75)
5
Figure 6: Integration of PV. Large Scale (left ), Building Integrated (Right')
The integration of photovoltaic sources of generation into buildings requires a deeper
understanding the challenges of innovation in the construction industry.
5 Picture from www.firstsolar.com (Accessed in September, 2012)
6 http://www.energystate.de/detail.php?lang=en&kat=project&id=94 (Accessed September, 2012)
31
2.3
Innovation Challenges in the Construction Industry
Four aspects distinguish innovation in the construction industry from innovation in
manufacturing industry: 1) most reliable testing results are obtained from full-scale
prototypes; 2) components are assembled on-site because of the large scale of the facility;
3) interactions with the constructed facility are not completely characterized because of the
longevity of use, the unconstrained type of users and uses, and the interaction with the
environment itself; and 4) design, construction, operation, and decommissioning activities
are constrained by codes and regulations (Slaughter 1998).
In particular, Slaughter showed that system integrators are likely to be a relevant source of
innovation in industries characterized by 1) technologies that require specific timely
information during the integration process, and 2) sophisticated users. In addition,
manufacturers can hardly replicate the innovation developed by system integrators because
the nature of applications is too broad and the cost to obtain precise information is too
high. Therefore, users - contractors - will likely be the main source of innovation in
connecting separate technologies into a whole working unit (Slaughter 1991); they have
information about and control over the affected components and systems during the
integration process.
Finally, Slaughter identified some specific activities and resources that need to implement
the innovation in the construction industry: 1) the timing of the commitment to use the
innovation, 2) the degree to which use of an innovation requires implicit or explicit
coordination among the different stakeholders, 3) the type and source of special resources,
4) the nature of supervision activities required. Slaughter used these four characteristics to
expand the innovation model developed by Henderson and Clark (Figure 3) to the
construction industry (Table 2) (Slaughter 1998).
32
Table 2: Specific Activities for Implementation by Type of Innovation. (From Slaughter 1998)
Types of
Innovation
Timing of
commitment
Coordination
within
project team
Special
resources
Supervision
organizational
level
Supervision
Sueiso
type
Supervision
Sprvin
competency
Incremental
At any time
None
None
At locus ofSpecific
improvement
Notification
product or
process
Modular
At
design/selection
For concept
change
At design level
None
Notification,
review
Technical
competency
Architectural
At design-toimplementation
Among
affected
parties
For
complementary
changes
At affected
system level
Notification'
agreement,
review
System
competency
System
At conceptual
design stage
With all
project team
members
For integration
of set of
innovations
At top
engineering
management level
Project scope,
agreement,
review
Technical and
system
competency
Radical
At technical
feasibility stage
For
breakthrough
Attop
management level
Project
objectives and
scope
Specialized
techmcal
competency
With top
2.4
management
from all
involved
organizations
System Architecture Principles
Within the fluid phase in the dynamic of innovation, where a dominant architecture has not
emerged, it is important to identify how system architects, or even investors, would
evaluate different system architectures. Having said that, this section summarizes ten
principles of systems architecture that might be helpful to consider.
1. A good architecture elegantly satisfies stakeholders' needs.
A good architecture satisfies stakeholders' needs by providing measurable benefits at
competitive cost elegantly and in a timely manner. The architecture should harmoniously
and independently arrange both functions and elements of form in order to transmit,
modify, resist or redirect objects as desired. This arrangement between form and function
defines the system's modularity, cost, complexity, safety, and aesthetics.
Edward Crawley indicates: "the aim of architectural design within system design is to
obtain the desired behaviors while suppressing undesirable behaviors. The system's
architecture is chosen to enhance achievement of these goals" (Crawley, de Weck, et al.
2004). Similarly, Nam Suh adds: "the best design is one where each function is
implemented in a way that is independent of implementation of any other function. This
permits maximum independency and simplicity" (Suh 1998).
33
2. The nature of the system relies on the interaction of its elements; the architect must
define the system's scale and scope to set his responsibility.
The essential properties of the system emerge from the interaction of its parts. By defining
the system's boundaries, the architect not only defines his accountability, but also sets
what are the supporting systems and objects that, through the system's interfaces, create
the required conditions that allow the system's emergence (Ackoff 1981).
Oliver de Weck et al. indicate that the specification of the system's boundaries is a specific
method to define the system scale and scope. On some occasions, the system's boundaries
are clear, but on others, they are abstract. When designing systems, system architects and
system designers have some freedom to design the elements inside the system's
boundaries, while the elements outside the boundaries are given by the context and cannot
be directly changed (de Weck, Roos and Magee 2011, 50-51).
3. Harmony not only rules the interactions within the functioning part of the System, but
also should be projected beyond the System's boundaries.
The architect of the system should not only look for essential complexity, maintaining
perceived complexity within the limits of what the human can understand, but should also
look for harmony between different types of interactions that rule the emergence of the
system, which optimally only can be determined accounting for the interactions of its
elements (Ackoff 1981).
4. The architect of sociotechnical systems should design for elegance, not for excellence.
Sociotechnical systems are profoundly shaped by perceptions. According to Mark Maier,
when the architecture of a sociotechnical system looses one foundation (e.g., technical
performance), it immediately gains another foundation (e.g., quick response to the public's
needs and perceptions) (Maier and Rechtin 2009, 125-136). By leveraging the system's
aesthetic, the systems architect contributes to relieve tensions between facts and
perceptions.
34
5. The architect should consider the material balance when architecting and designing a
system.
There are three opportunities to focus on the balance of the system: first, analyzing the
objects of form; second, analyzing the processes of attribute transformation, and third,
considering together the first two options within an expanded view of the System and its
beneficiaries. The last alternative offers the highest opportunity for value creation and
sustainability.
According to the architect and industrial designer David Pye, what we see of a device is
hardly its essential part, but regularly the structure which economy has imposed on it.
Economy can exercise a powerful influence upon the appearance of systems; however,
economy never does in fact govern appearance because the requirements for economy will
be in conflict with the system's aesthetic (Pye 1995, 33 and 69).
6. The architect should define and consider those system properties that matter once the
system has been put to its initial use.
The ilities are not the primary functional requirements of a system's performance, but are
desired properties of the systems, such as quality, safety, operability, maintainability,
flexibility, resilience, sustainability, scalability, modularity, evolvability, adaptability,
interoperability and so forth, that often manifest themselves after the system has been put
to its initial use. The systems architect should consider ilities when designing the system
(de Weck, Roos and Magee 2011, 65-96).
The ilities are influenced by increased complexity of the system and changing social
values. The architect should consider that, from the stakeholders' perspective, some ilities
are more important than others. In addition, different ilities become more important over
time (de Weck, Roos and Magee 2011, 65-96).
35
7. The right modularization emerges after analyzing the second level of decomposition of
the system
According to Baldwin and Clark (Baldwin and Clark 2000, 89-92), modularity contributes
to achieving three objectives. First, it facilitates the management of complexity by limiting
the range of interaction between elements or tasks. Second, it enables the simultaneous
development of different parts of a large design. Finally, it creates options that help to limit
risk by accommodating uncertainties.
Systems can be decomposed by functionality, elements of form, or a combination of both.
Modularization enables the architect to limit complexity and leverage understanding of the
system. The right modularization is achieved after analyzing the second level of
decomposition of the system; only by understanding the interrelation at such a level can
the architect define the right modularization at the first level of System's decomposition
(Crawley 2011 c).
By defining the right modules, their function and their interfaces, the architect can
efficiently: distribute design work; distribute fabrication and implementation; allow for
easier
integration;
promote
service/upgrade/replacement;
understanding
during
operations;
allow
for
allow for cross-project standardization; and design for
flexibility (Crawley 2011 c).
8. Design for multiple beneficiaries to increase the value creation
David Pye states: "no matter how intractable his problem may be, the designer has a
responsibility to far more people than those who pay him and those who use what he
designs" (Pye 1995, 94). Systems have different upstream and downstream influences. The
action of the system might also influence different stakeholders and users in different use
contexts. By understanding stakeholders needs and jobs need to get done within different
use contexts, the system architect can design a system that produce different outcomes,
benefiting a variety of stakeholders' needs.
36
9. Complex multi-stakeholder projects must be committed to exchange value to fulfill both
direct and indirect stakeholders' needs
The system has beneficiary stakeholders and problem stakeholders; both have needs that
are either directly or indirectly related with the system. The project will be successful when
it harmoniously pursues value delivery reciprocity, which means that the project provides
something that its stakeholders need. The function provided should be intrinsically related
to the outcome of the system (Cameron, et al. 2011).
10. Regarding the relevance of the supporting systems to the success of the system, that is
being designed.
The architect of the system should understand the context and elements that are necessary
for the system to be. When putting the system into place, all supporting systems must be in
place in order to obtain its emergence right (Crawley 2011 b).
37
Chapter 3 - BIPV Faeade Artifacts - Use Context,
Needs and Objectives
The System of Interest
3.1
The system of interest is afagade artifact that can transform solar energy into electricity,
hereafter, the Fagade Photovoltaic Artifact (FPVA) -
details in Section 3.3. When several
FPVAs are assembled with a balance of system 7 , and other traditional fagade systems (wall
panels, windows, load-bearing structure, etc.), the resulting system constitutes a Building
Integrated Photovoltaic (BIPV) fagade system (Figure 7). As explained in Section 3.2.3,
BIPV fagade systems have different functions and are one of the alternatives by which
photovoltaic systems can be integrated into buildings (Figure 10).
Use context
*
*
*
*
Energy Purchase, Energy Consumption, and Sustainability Goals
Policy Drivers (near zero energy building regulation, standards, codes, policies)
Climate (insolation conditions, temperature range)
Social Awareness (aesthetic)
nZE Building
BlVad
aa
Buildin
S
Traditional
fagae
components
Systems
that
transform
Energy
(Oas)
Energy
Connection
BDistribution.
to Utiity
Buing
Metering and
Systems
Management
Systems
Fgd'
aladerin
Strutur
Assembly
components
Balance of
System-
Supporting Systems
Figure 7: System of Interest in Context
7
The Balance of System consists of the PV combiner, the grid inverter, electrical cables,
and the meter and grid connection.
38
The BIPV fagade system will likely be part of a building that aims to decrease its energy
consumption from utilities and locally produce sustainable energy. In some cases, the
emergence would be a near-zero energy building (details in Section 3.2.1). In general,
BIPV systems are developed in a business context with 1) defined policy drivers by which
regulators have defined not only new standards for energy consumption in buildings, but
also electricity tariffs and tax incentives, 2) high sustainability standards valued across the
business's value chain, 3) good solar insolation, and 4) high environmental awareness and
positive perception towards renewable energy.
3.2
Why the System is Built. Need Opportunity.
BIPV fagade systems have mainly three beneficiary stakeholders8 : the government, the
owner of the building, and the user of the building (the owner and the user of the building
can be the same agent). Table 3 summarizes the needs for each beneficiary stakeholder.
8 Beneficiaries:
"Are those who benefit from the product's actions. The product has an
outcome that addressed their needs. The product is important to them" (Crawley 2011).
39
Table 3: The Need Opportunity
Need
Beneficiary
Government
1. Increase energy conservation in residential and commercial buildings, which account for
40% of the energy consumption in Europe and U.S. (DOE 2007) (Federal Executive Order
#13514 2009) (European Parliament 2010).
2. Efficiently and environmentally friendly power the energy needs of the society
incentivizing the use of local renewable sources to supply distributed demand.
3. Reduce the rate of consumption of fossil fuels.
4. Create a new industry that provides sustainable employment and fair wages.
Owner of the
1. Have a building with electricity supply.
2. Decrease energy expenses.
Building
(Investor)
3. If ruled, comply with governmental standards regarding the use of local renewable
sources to supply energy consumption in buildings (European Parliament 2010).
4. Comply with corporate sustainability goals, if defined.
5. Make a profit (ROI) either by taking advantage of governmental incentives (e.g. Feedin Tariffs, Tax Credits, etc.) or by developing a compelling business plan without support
of governmental incentives.
6. Have a building that meets specific aesthetic standards to promote corporate image.
User
of the
1. Have a building with electricity supply.
2. Decrease energy expenses.
Building
3. If ruled, comply with governmental standards regarding the use of local renewable
source to supply energy consumption in buildings.
4. Comply with corporate sustainability goals, if defined.
5. Have a building that meets specific aesthetic standards to promote corporate image.
3.2.1
Near-Zero Energy Buildings
In an attempt to answer how might we fulfill energy needs of new buildings, regulators
have come up with the ideal9 to make all new buildings an efficient and reduced energy
consumption system locally supplied by renewable energy systems so as to result in no net
emission of greenhouse gases. This ideal was synthesized in the concept known as zero-
9 "Ideals:
ends that are believed to be unattainable but toward which progress is believed to
be possible." (Russell Ackoff, pg. 104)
40
energy building. However, in the near term there are factors that have constrained the
large-scale development of autonomous buildings, locally supplied with renewable energy:
1) renewable sources are intermittent; 2) energy conversion efficiency of distributed
renewable sources is low -
albeit increasing; 3) clean energy sources and energy storage
systems are not yet economically deployed for large consumptions; and 4) energy
consumption patterns are difficult to adjust to the availability of renewable sources.
Nevertheless, the development of near-zero energy buildings in which there is a balance
between the energy consumed from utilities (i.e., gas, electricity) and the energy supplied
back to the utility over a period of time can be achieved. In fact, it is an objective for
several governments (DOE 2007) (Federal Executive Order #13514 2009) (European
Parliament 2010).
A near-zero energy building can be associated with the idealized design concept,
developed by Russell Ackoff (Ackoff 1981,
104-107). An idealized design is a
representation of the system that its designers would like to have right now, not in a future
state; therefore, the environment in which the system would have to operate does not need
to be forecasted -
it is the current environment. However, assumptions about future
conditions in which the system will have to operate should necessarily be considered into
the design. In the case of near-zero energy buildings, these conditions are the renewable
energy production and the expected energy use. According to Ackoff, idealized designs
have three characteristics; they are "technologically feasible, operationally viable, and
capable of rapid learning and adaption" (Ackoff 1981, 105).
The development of near-zero energy buildings comprises different aspects: first, the
reduction of the energy needs in buildings; second, the production of electricity using local
renewable energy sources; third, the management of the utilization of the electric
distribution grid to supply energy to consumers and receive the energy generated by
distributed resources; and lastly, the definition of systems that manage the interactions
between the different elements and provides information not only to the user, but also to
41
other stakeholders that might need information about the state of the system (Sartori,
Napolitano and Voss 2012)10 (Hickey, et al. 2012)."
Even though the concept of near-zero energy buildings could appear simple, immediately
as the design and implementation complexity increases, and many aspects such as the type
of energy and loads considered in the energy balance, the balance period, the suitable
metrics, and the accounting procedure need to be accurately defined (Sartori, Napolitano
and Voss 2012) (Voss, Musall and LichtmeB 2011) (Marszal, et al. 2011). Nowadays,
many of these aspects have been neither defined nor standardized. Figure 8 summarizes the
concept of near-zero energy buildings (Sartori, Napolitano and Voss 2012).
The conceptual design of a near-zero energy building shall consider assumptions not only
regarding the climate conditions where the building will be developed, but also the human
factors driving the building use, the expected load profile, and some design parameters
10 In order to have a common understanding of the concepts involved with near-zero
energy buildings, it is important to present some definitions:
1. Building system boundaries: Boundaries through which energy flows in and out of
the system will be compared.
2. Energy Grids: The systems through which the building receives energy from outside
the system's boundaries (electricity, gas, etc.)
3. Delivered Energy: Energy flowing from energy grids to the building in a defined
period.
4. Exported Energy: Energy flowing from the building grids to the utility's grids in a
defined period.
5. Load: Building energy demand, specified in each of its different forms (electricity,
gas, heat, etc.) in a defined period.
6. Generation:Building energy generation in a defined period.
7. Weighting system: It defines how to convert the physical units into a desired metric.
8. Net Balance: Difference between the total energy supply and the total energy
demand.
" The interaction between the near-zero energy building and the utility grid should be
carefully analyzed because as the number of increasing distributed energy sources
increases, so too the grid's operational volatility. Therefore, stability, safety and quality
problems might emerge at distribution level. In addition, stakeholders will need
information to assess the level of achievement of the consumption/generation balance.
42
related to the building enclosure and the on-site generation -
BIPV systems are one of the
alternatives that can be used to provide on-site power.
building system boundary
Weighting system
[kWh, CO. etc.]
weighted supply
weighted demand
Net ZEB balance
Figure 8: Connection between buildings and energy grids (from Sartori 2012)
As society stands today, evolving people's expectation and human needs will likely drive a
paradigm shift in both energy use and building regulation. The integration of renewable
sources in buildings, and particularly the eventual near-zero energy consumption goal, will
increase the complexity not only of the building design and construction processes, but
also of the interactions that consumers have with their energy provider.
This trend can be easily associated with the Tim Brown's vision (Brown 2009, 178), which
emphasizes: "a change in expectations is blurring the line between products and services as
consumers shift from the expectation of functional performance to a more broadly
satisfying experience." He adds, "We might likely be entering to an era of limits, in which
mass production and mindless consumption are not longer possible."
No doubt, building integrated photovoltaic systems will make unclear the line between the
product -
the BIPV fagade system or the near zero-energy consumption building -
the service -
and
supply electricity to buildings. Moreover, if economic signals define strong
43
incentives to maintain the building's energy balance over a period of time, such a goal will
likely drive the need to carefully monitor the two main process variables: local renewable
generation, which cannot be controlled, and energy consumption. This process would
represent the end of bulk energy supply and mindless energy consumption for users in
buildings. Figure 9 summarizes this situation. One open question is how we should design
a near-zero energy building system capable of rapid learning and adaptation in order to
permanently achieve its goal.
Regulation
nZE Building
Building
Integrated
Photovoltaic
Systems
Complex
EvolvingEvoling-Blurrng
of the
people's
expectations
line bet**en
Corporate
Goals
product and
services.
Sustainability
Era of Limits
Mass Production &
Mindless Consumption
NO longer possible
/
4%
Reference
consumption
Energy Efficiency
Energy Consumption
Figure 9: Near-Zero Energy Buildings
3.2.2
Building Integrated Photovoltaic (BIPV)
Photovoltaic systems can be installed either in the field, on the top of the existing building
structure, or integrated into the conventional building as part of the building's envelope,
creating a harmonious architecture (Marsh 2008) (Pagliaro, Ciriminna and Palmisano
2010) (Henemann 2008). Currently, each alternative has advantages and disadvantages,
which are summarized in Table 4 (Kiss & Company Architects 1995) (Steven, Hoepfner
and Reinhart 2012).
44
Table 4: Advantages and disadvantages of different types of PV systems
Field-Mounted PV
A d %a n tag(es
D)isa d Na n ta ges
1. Unconstrained Orientation implies nearoptimal energy yield.
1. Land cost
2. Use of tested solar products.
Building-Mounted PV
3. High modularity and flexibility after
implementation.
3. Might not be considered inside the
system boundaries for near-zero energy
buildings.
1. Design could be defined in any stage of
the building development. The sooner, the
better.
1. Orientation partially constrained by the
building structure. Might affect the
electricity production.
2. Simple addition onto the building.
2. Potential structural complications and
waterproofing risk.
3. Use of tested solar products.
4. Considered inside the near-zero energy
building's system boundaries.
5. Opaque PV systems installed in
shadings decrease the building's solar
gain.
Building-Integrated PV
2. Supporting structure cost.
1. Structural and installation synergies.
2. Harmonious
compatibility.
integration,
aesthetic
3. Considered inside the near-zero energy
building's system boundaries.
4. Some designs can
building's solar gain.
decrease
the
5. Light-through PV systems can
contribute to decrease daytime electric
lighting.
3. Requires Compatibility with building
codes.
4. If installed on roof, it might increase
cooling load compared with white roofs.
5. Risk of partial shading, especially if
mounted onto fagades (Sick and Erge 1996,
27).
1. Orientation constrained by the building
design. Affects the electricity production.
2. Potentially
12
temperatures
higher
PV
operating
3. Requires Compatibility with building
codes.
4. Potential structural complications and
waterproofing risk.
5. Design should be defined in early stages
of the building design. Adoption for
retrofits might be limited.
6. If installed on roof, it might increase
cooling load compared with white roofs.
7. Low modularity and flexibility after
implementation.
8. Lack of uniform size and standards in PV
modules.
9. Risk of partial shading, especially if
mounted into fagades (Sick and Erge 1996,
27).
1 In curtain wall spandrel areas, heat behind the PV modules produces thermal stress,
reduces the PV energy conversion efficiency and can induce heat gain into the building. In
order to reduce these risks, ventilation systems should be considered.
45
Figure 10 shows three application segments for BIPV: Fagades, Shading, and Roofing
Systems (Kiss Cathcart Anders Architects, P.C. 1993). 13 Regarding the integration of
BIPV systems in the context of near-zero energy buildings, an important design factor is
the ratio between the vertical surface and the horizontal surface of the building.
Nevertheless, generally, tall buildings are located in highly populated areas, where they
could be more susceptible to shading effect by nearby buildings.
In this context, building fagades are considered good candidates for developing BIPV
systems because they constitute the larger surface available on large buildings, although
vertical fagades do not provide the best output for photovoltaic systems (details in Section
3.2.2.1).
BIPV - SYSTEMS FOR FAgADE AND SHADING
BIPV
-
ROOFING
SYSTEMS
Figure 10: Types of Building Integrated Photovoltaic Systems (EnergyGlass)
The primary function of a photovoltaic system -
to convert solar energy into electricity
can be easily associated with a photovoltaic system either installed in the field or added
on top of the building structure. However, as presented in Section 3.2.3, once the
13 There are different types of fagades: rainscreen, stick-system curtain wall, unitized
curtain wall, double-skin, etc.
46
photovoltaic system is integrated in the building structure, other functions such as
waterproofing, resisting heat transfer, transmitting visible electromagnetic radiation, and so
forth, will be equally important for the BIPV system as a whole. In this context, the
question of what is the system's primary function and the system's primary source of value
becomes important.
A multi-functionality approach for BIPV systems needs to be addressed in order to
understand not only what might be the system's primary source of value, but also whether
there might be any conflicting functionalities that require design trade-offs. The integration
of new, novel functionalities into building materials is a difficult task because of the
absence of specifications, components factsheets and testing certificates. In this context,
the confluence of three different highly regulated and standardized sectors engineering, electrical engineering and building legislation -
construction
has initially created barriers
for further development and standardization of BIPV systems (Henze, et al. 2011).
The systems engineer and systems architect Eberhardt Rechtin (Rechtin 1990, 69)
emphasizes some specific aspects that need to be clarified when addressing the decision to
define a single or a multipurpose system. In the context of BIPV systems, those aspects
are: Is the resolution to conflicting needs simple? Does the single purpose BIPV result in
more control over the design and operation of the end system? Is the single purpose BIPV
more expensive than the multipurpose? Does the multipurpose BIPV leverage the system
economics by sharing costs into different functions? Is the value of a single purpose BIPV
vulnerable so as to create the need to look for backup functions? Is the multipurpose BIPV
more powerful, flexible and resistant to stress over its life cycle? Does the multipurpose
BIPV system cost less overall?
For example, BIPV systems can reduce infrastructure and installation costs of the
photovoltaic system by leveraging synergies in building and material integration. The
value of the BIPV system can be greater than that of a building and a photovoltaic system
taken separately; however, the emerging value will depend on the electricity generated as
well as on other factors such as the thermal gain, the insulation features, the energy prices,
the durability of the materials, and other constructability features.
47
Nevertheless, it would be more feasible to achieve the benefits when the system (the
building and the PV system) is designed and integrated in early stages. As presented in
Table 2, when the intent is to develop systemic innovation in the construction industry, the
timing of commitment shall be during the conceptual design phase.
3.2.2.1 The Physics behind a BIPV System
It is important to understand how the system acts. As highlighted by David Pye (Pye 1995,
23-25) a good architecture must ensure that the systems correctly embody the essential
principle of arrangement because every useful invention is a discovery about the way
things and energy can behave.
A surface perpendicular to the sun's rays at the sea level receives approximately 1000
W/m 2 on a clear day. The total radiation energy can be separated into direct beam radiation
and diffuse solar radiation (Firmanda Al Riza, Ihtsham ul Haq Gilani and Shiraz Aris
2011). Approximately 44% of sunlight energy that reaches the earth is visible; 52% is
infrared (NREL).
The conversion efficiency of BIPV systems will depend on the technology. For current
commercial systems, the conversion efficiency can be anywhere from 1% to 24%
(International Renewable Energy Agency 2012). Therefore, from 76% to 99% of the
energy is, in different proportions, reflected, converted into heat, and transmitted to the
interior of the building. As BIPV systems are embedded into building envelope, heat
dissipation could be a factor that affects the conversion efficiency and the photovoltaic
material life expectancy (Steven, Hoepfner and Reinhart 2012).
Regarding BIPV systems' orientation, the vertical angle has a striking effect on energy
yield performance, while, in contrast, the orientation between southeast and southwest is
less relevant (Roberts and Guariento 2005, 34).
These effects have profound implications in the design and installation of BIPV systems
for vertical curtain wall applications. First, there is an important friction in the design of
light-trough PV system -
transparence versus energy density (see next chapter). Second,
48
the orientation of BIPV has energy production, and consequently economic, implications
-
roofs or inclined surfaces will be preferred (Figure 11).
levelof Insolation
compared
to the maximum
tiltanglefromhorizontal
w 4M
.57
Figure 11: Comparative total insolation over a year for all angles of tilt from horizontal and orientation building located in Freiburg, Germany (Roberts and Guariento 2005, 34)
In addition, as the BIPV fagade system will separate the building's interior from the
building's exterior, the BIPV fagade system may have to resist heat transfer because the
temperature range that users define as their comfortable zone can be significantly different
from the ambient temperature outside the building. The greater the ambient temperature
range outside the building compared with that required inside the building, the greater
should be the thermal resistance requirement for the building fagade1 4 in order to preserve
the temperature inside the building.
Technical properties of fagades are: thermal transmittance (U-value), total solar energy
transmittance (g-value), visible transmittance, and visible reflectance (Wilson 2004).
49
14
3.2.3
BIPV Faeade Systems
FPVAs will be integrated in building fagades, which are systems that contribute to
communicate purpose and create context by influencing the space in and around the
building. The design choices in the building fagade significantly affect the building's
energy consumption. As illustrated in Figure 12, by separating the building's interior from
the outside environment, the fagade provides several functions that need to be considered
during its design and construction (Knaack, et al. 2007, 70):
- Defines the appearance of the building,
e
Allows views to the inside and outside,
e
Absorbs forces from wind and snow loads, as well as that of live loads,
- Sustains its self-weight as well as other building components,
e
Allows sunlight to penetrate into the building, while often providing protection from
sun at the same time.
e
Resists the penetration of water,
e
Handles humidity,
e
Provides thermal insulation,
e
Provides acoustic insulation, and
e
Can provide energy generation.
50
Natural lighting
Protection against UV-radiaion
Energy genation
view out
Ventilation
Push and pull forces
frown wind koads
-
Vapour diffusion
No
5)e
-
,
'
Heatcold insulation
s
Appearance of
building in urban context
Self-weight
Figure 12: Faeade functional requirements (Knaack, et al. 2007, 36)
The aforementioned functions cannot be attributed to its components individually; they
emerge at the system level. Figure 13 shows how the needs are associated with different
functions. For example, the fagade contributes to keep the heat either indoor or outdoor the
building by 1) reflecting energy, which has the attribute of radiant heat, and 2) resisting
energy, which has the attribute of conductive heat.
51
When we observe the needs that have to be satisfied, questions regarding the goals of
performance and the different functions that the system shall accomplish, and the system's
form structure required in order to perform those functions have to be addressed.
Separating
Allowing pass
Reftlcing
Mih
Resisting
Perliormance
Energy
Generating
Inspiring
Creating
Powering
Figure 13: Faeade functional requirements and concept
Nevertheless, uncertainties in regards to market needs and the end purpose of the system
should not be discarded, particularly in new, emerging markets. The uncertainties of end
purpose can have serious consequences in decisions affecting the system design,
development, and production, leaving the system developers vulnerable to work on the
wrong problem (Maier and Rechtin 2009, 61).
52
3.3
Faeade Photovoltaic Artifacts (FPVAs)
3.3.1
What the system accomplished
The concept of FPVA is defined by augmenting
5
current fagade systems, i.e., adding an
energy transformation module and an electronic & connector module into conventional
fagade systems. Figure 14 represents the concept and the flow chart of BIPV fagade
artifacts. A strategic, early design decision ties in the visibility of the added modules in the
context of the larger system within which FPVA systems are installed. The higher the
visibility, the higher the coordination required with the system's architects and, even, with
users.
Once integrated into a building fagade, FPVAs must efficiently separate the interior from
the exterior of the building, while generating electricity from electromagnetic solar energy.
FPVAs could have either of the following attributes: opaque, semitransparent (lightthrough) or transparent artifact. From the socio-technical perspective, both opaque and
semitransparent artifacts have visibility from the user's perspective; this visibility will
require different degrees of coordination from the civil architect's point of view.
-u=
0r-M Olina
MMubla
Inie
rnsMd
a
Frame
mean7 POTOVO.TAC
AR
Figure 14: Functional representation of the concept (Knaack, et al. 2007, 130) (left). Simplified flow chart of the
design of the system (right)
1
The augmenting operator is defined in Baldwin and Clark 2000, p. 301-307.
53
Systems architecting cannot be defined in the abstract. According to Maier (Maier and
Rechtin 2009, 62), architecting has to be grounded in the strategies of the organization
developing it. Maier emphasizes that in order "to reconcile how architecting and
architecture relates to competition, we must set the context of the organization overall
competitive strategy." In this context, the design of FPVAs should consider needs across
the system's value chain. The regulations, company's corporate and marketing strategy,
customer's needs, competitive environment, and technology, constitute the dominant
upstream influences on the architecture of FPVAs. In addition, the system is influenced by
needs of architects, developers, installers, operators, and buildings, which constitute the
downstream influence on the system (Figure 15).
Dominant Upstream Influence
Dominant Downstream Influence
Need1?Implementation
....
...
Regulation
Corporate,
Marketing
1
Architect,
installer)
Th)I
- ...
?
r
Strategy
-
Customers
(Developer,
1
Architecture
Form
Operations
Need
Operational cost
SConcept
Competitive
Environment
Downstream m..dli.er?
strategies, LJ.......J
Competence
Technology
Need ?
I
1dEvolution
Design
Figure 15: Influence of stakeholders in the Product Architecture (adapted from Crawley 2011)
Marc Meyer (Meyer 2007, 82-87) explains the importance of revealing needs through use
case scenarios.16 This suggestion implies that developers of FPVAs should consider 1) the
Use case scenarios describe the complete number of activities that the user experiences
in using a system, considering different use phases: before, during, and after. In some
cases, the users can be different in each use phase; consequently, all users need to
understand how the product works for the job that they need to develop.
54
16
jobs that need to be done by users of buildings, and the factors driving those jobs, and 2)
and the jobs done by architects, developers, and installers.'7 The second category is
important because architects, developers, and installers are the key stakeholders that allow
the adoption and integration of FPVA. They are the agents of beneficiaries -
beneficiaries
are the government, and owners and users of buildings, as described in Table 3. Architects
and developers identify the product and the opportunity to create value.' 8
3.3.2
Types of PV and FPVA
FPVAs are fabricated in several different ways, depending on the PV material,
encapsulation method, electrical connection, and other factors. FPVAs can be either
opaque or light-through panels, which can be semitransparent or transparent.
Currently there are different families of photovoltaic technologies. The first generation
mainly entails monocrystalline, multicrystalline, ribbon silicon cells; the second generation
includes amorphous silicon, copper indium selenide, cadmium telluride, micromorph Si
cells; lastly, the third generation includes dye sensitized solar, polymer cells (organic), and
quantum dots. Figure 16 shows the evolution of the best research-cell efficiencies since
1975, highlighting the different families of cells that have been developed over time (blue
and purple: first generation of cells; green: second generation; red: third generation)
(International Renewable Energy Agency 2012).
The concept ofjobs was introduced by Clayton Christensen (Christensen, Anthony, et al.
2007).
17
Value emerges by incorporating a product, the intent of which- to separate the interior
from the exterior of the building, while generating electricity from electromagnetic solar
energy - satisfies customers needs at competitive cost.
55
18
DNREL
Best Research-Cell Efficiencies
50
Mulijunction Cels (2-temial. monolithic)Thin-Film Technologies
vThree-junclion (concentrator)
v Threeuncion (non-concentrator)
A Two-juncion (concentrator)
48 -
44 - S~~md~ &
36-
poly-Si
* Nano-,
micro-,
poycrystalline
A Mullgunchon
Emerging PV
ODye-sensitied
Aconcentrator
V ThinFimcrystal
40-
e Cu(In.Ga)Se2
o CdTe
0 Amorphous
Si:H(stabilized)
C9tin.&Cobs
A Organic anoe
A
cells
0 WkrysJIahn
0
32
SingOyrgac
fllilnI dot cells
* Sion Hetenostructres
(HIT)
28NR
Westin Spir
Vrian
UNSW
Tec
20
12 -
r
AE
Kodak Bo
8
S
UnivCrsy
40-
o
nde
ACOi
EPL
A
Figure 16: Evolution of best research-cell efficiencies (NREL)"'
Figure 16 also represents how the dynamic of the industry has unfolded at the commercial
level, 2 0 and can provide some insights about the medium-term expected evolution of
photovoltaic technologies. For instance, it could be argued that thin film technologies
would likely be under pressure because, while the conversion efficiency of the thin film
technology seems to have reached a stable level, on the one hand, Silicon technologies are
increasing their efficiency, and, on the other hand, the third generation of photovoltaic
technologies is rapidly increasing its energy conversion efficiency. Therefore, in terms of
energy conversion efficiency, the thin film technology would likely be in the middle of two
technologies that are still evolving: one from the top, and the other from the bottom.
Nevertheless, as opposed to organic cells, thin film and Si-PV technologies have long life
span (Garcia-Valdeverde, Cherni and Urbina 2010) (Renewable Energy World 2008)
(International Renewable Energy Agency 2012) (Lewis 2009).
19 Source: http://www.nrel.gov/ncpv/images/efficiency chart.jpg (Accessed in September
2012).
20 Even though the concentrated photovoltaic technology has not been commercially
adopted.
56
On average, the price of PV systems has decreased significantly since 2006 (Figure 17). In
addition, particularly in the Germany, non-hardware costs for residential PV have achieved
significant efficiencies and economies of scale as the installed capacity of PV systems in
the country has grown (Seel, Barbose and Wiser 2012). It is important to remark though
that cost of overhead, labor, installation materials, and other indirect costs (in terms of
$/W) are inversely related to PV efficiencies (James, et al. 2011). Therefore, the use of low
efficiency FPVA has effects that are projected beyond the system boundaries, also
affecting the cost of the balance of system (in terms of $/W).
12
10
-
-
V4
6
4
6.21
0 6.56
US system prices
-
German system prices
....
module factory-gate prices
CA
-
2
0
-
*NJ
1.81 i
1.35AZ
2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011
Figure 17: Median installed price of customer-owned PV Systems
slOkW. (From Seel, Barbose and Wiser 2012)
In the context of FPVAs, the aforementioned photovoltaic technologies can be integrated
into different systems. Even though, in essence, the architecture of different FPVAs has
some similarities (at a very high level the architecture is based on the concept presented in
Figure 14), there are differences regarding the architecture of the energy transformation
module; the characteristics of other modules that are utilized; and the approach by which
the tension between the electromagnetic-energy
transformation function and the
electromagnetic-energy transmission function is resolved in the fagade system. Figure 18
summarizes different concepts of FPVAs that currently are being developed either at
commercial scale or research level. Figure 19 depicts some examples of fagade BIPV
systems and technologies that have been developed.'
Chapter 4 presents a qualitative
analysis of the architecture associated with these concepts.
Images from: 1. Opaque BIPV crystalline cells (European SunRise Project). 2. Opaque
BIPV thin film (Onyx Solar 2012). 3. Spaced crystalline solar cells (Henemann 2008). 4.
57
21
Cocept 1: opaque WPV Syems - crystaxne cela and mti Imw
Concept 2:
Spaced Cells
Concept 3:
Solar Refector
Concentrator
Light-through
BIPV Systems
I
Spaced Crystalllne Solar Cells
Laser grooved thin film cell
Prism & Crystane Solar ces
Organic dye &Crystalline Solar Cells
Very thin im solar cell
Concept 4:
Translucent
Semi-transparentpolyme solarcelgs.
Dye-Sensized Solar Cells
Cncept 5: Transparent
Visibly transparent polymer solar cells
(Capture photons from IR Spectrum)
Figure 18: Different types of Faeade BIPV Systems
1. Opaque BIPV
crystalline cells
flm
4. Laser grooved thin
film cell
2. Opaque BIPV thin
5. Dye-sensitized
solar cells
7. Semi-transparent
organic solar cells.
3. Spaced crystalline
solar cells
6. Solar reflector concentrator
prism & crystalline solar cells
8. Transparent organic
solar cells.
Figure 19: Different types of Faeade BIPV Systems (examples)
Laser grooved thin film cell (MakMax TAIYO KOGYO CORPORATION). 5. Dyesensitized solar cells (Dyesol). 6. Solar reflector concentrator prism & crystalline solar
cells (Pythagoras Solar). 7. Semi-transparent organic solar cells (Konarka). 8. Transparent
organic solar cells (Chun-Chao Chen 2012).
58
The energy conversion efficiency of different technologies is summarized in Figure 20.
The data has been obtained from scientific publications, product sheets, and, in some cases,
interviews with companies' representatives (International Renewable Energy Agency
2012) (Lunt and Bulovic 2011) (Currie, et al. 2008) (Chun-Chao Chen 2012) (Pythagoras
Solar) (Invisergy) (Onyx Solar 2012) (Konarka) (Solamer) (MakMax Taiyo Kogyo
Corporation) (Dyesol) (SolarWindow) (Covalent Solar) (Guardian SunGuard) (Mage
Sunovation) (Schott) (Schuco) (Ertex Solar) (Sapa Solar) (Scheuten Solar) (Sun Power)
(Galaxy Energy) (Energy Glass) (Dupont) (TropiGlas) (Odersun) (Oxford Photovoltaics)
(Ubiquitous Energy) (Heliatek).
Based on the energy conversion efficiency and the transparency percentage characteristics,
a FPVA efficiency-possibility frontier has been qualitatively defined (red line, Figure 20).
As the technology is evolving, efficiency will increase during the coming years.
Performance Comparison of Faqade Photovoltaic Artifacts
26
24
22
Energy Conversion Efficiency and Transparency Frontier
C
10S12Thin
Film PV
SolarReflector Concentrator
Se;Wnf=aspen Thin Film
Solar
Reflector Concentrator
2
0.
0
10
20
30
40
so
0
70
80
Transparency (%)
Figure 20: Comparison of faeade photovoltaic artifacts (efficiency vs transparency)
Conventional, opaque panels have the highest efficiency. Systems based on the spaced
crystalline solar-cells concept have a wide range of transparency, which is easily defined
by the space between cells in a given glass surface. The solar reflector concentrator
concept is perceived as an alternative that can achieve both a relatively high efficiency
because it utilizes conventional silicon PV cells and fair transparency 59
as technically
perceived by the architect. Systems with high transparency (60%-70%) currently have less
than 6% of energy conversion efficiency and are still at an early stage of development.
In addition, it is important to consider the life expectancy of the PV system. Materials
commonly utilized in building fagades or roofs generally endure more than 20 years. In
that regard, BIPV systems should have a life span compatible with that expected for
materials in the building industry.
Silicon PV and thin film cells may remain in good condition for more than 20 years. While
on-site evidence is limited, most studies are based on laboratory tests and models (Vizquez
and Rey-Stolle 2008) (Jordan 2011) (Sample 2011). Organic cells currently have a limited
life span. If the life span of FPVAs is significantly different than that normally expected
for materials in the building sector, the adoption of BIPV will be constrained and,
consequently, will remain far behind the adoption of PV systems mounted onto of the
building infrastructure.
FPVAs can also be highly customized. Customization can be achieved by using different
sizes, colors,
architectural
designs,
and transparency
levels. Flexibility through
customization may be an important driving factor for architects, who usually desire to
design buildings with a sense of uniqueness. However, there is a trade-off upstream in the
value chain because customization and manufacturing and supply chain flexibility are
achieved at expense of cost.
In addition, from the functional and aesthetic point of view, BIPV artifacts compete with
several non-glass materials22 and glazing systems.23 In some cases, non-glass materials and
glazing systems can be even more expensive than BIPV systems (European SunRise
Project) (Steven, Hoepfner and Reinhart 2012). Nevertheless, conventional materials have
currently several advantages. They are basic materials that are well known by architects,
22
Marble, louvers, parapet unit, etc.
Transparent glazing (clear float glass, tempered glass, tinted float glass,
laminated glass,
reflective glass, low-emissivity glass), semitransparent glazing, opaque glazing, insulating
glazing.
60
23
developers and installers; in addition, they have low installation complexity and long
durability, and are simple to modularize.
Figure 21 presents four high-level market segments that are considered by companies
designing FPVAs. These segments are intrinsically associated with early-stage decisions
that define the architecture of the system, and consequently its performance. On the one
hand, the decision to design either an opaque or a light-through PV system ties in with the
system's electric power density -
the next chapter relates this characteristic with the
friction between the building aesthetic and users' perceptions. On the other hand,
companies should define whether to design customizable or standardized products.
Electric
Power
Density
Opaque PV
System
Lightthrough PV
System
Custom made
BlPV product
Standardized
BIPV Products
Figure 21: BIPV product market strategy
3.4
Stakeholders
It is difficult to effectively answer whether fagade BIPV will remain in a selective niche
market, expand beyond niche markets in the long term, or decline its rate of adoption in
niche markets. Transitions in sociotechnical regimes are influenced by complex
interrelations between stakeholders, regulation and legacy systems (Geels and Schot 2007).
Complex engineering systems are composed of tangible and intangible components that
61
interact between social, functional, process, technical and environmental domains, and
evolve over time (Figure 22).
In this context, system architects should understand the relationship among system drivers,
stakeholders, objectives, functions, objects, and activities (Bartolomei 2007). Based on the
Design Structure Matrix (DSM) tool, Bartolomei proposed a new representation that
allows a better understanding of the relationships between high-level needs and system
drivers and the solutions that are implemented.
0*~
tpmw.A
Figure 22: Interactions in complex engineering systems (From Bartolomei 2007)
Figure 23 categorizes the stakeholders into one of three categories: beneficiary
stakeholders, those entities who need the project, for whom the project is important;
problem stakeholders, those entities who provide resources to the project but receive little
or no benefit; and charitable stakeholders, who receive benefit from the project, but do not
directly provide resources to the project (Crawley 2011). Stakeholders can be either
directly or indirectly related with the project (the focal organization). Feng et al. presented
a method to assess the relevance of different stakeholders and their interactions. The
method can be used to improve the definition of the system requirements. It has been
62
demonstrated
that indirect
stakeholder relationships
can have
relevant strategic
implications in engineering systems (Cameron, et al. 2011) (Feng, et al. 2012).
In the case of fagade BIPV systems, problem stakeholders include the governmental
agencies, architects, electric distribution companies (utilities), investors, media, and other
fagade-technology suppliers. In addition, beneficial stakeholders include the building
owner, direct users of buildings, developers, installers, and BIPV supporting system
integrators. Benefits are received in different stages of the project life cycle; while
developers and installers receive benefits at an early stage of the project life cycle, building
owners and users receive the benefit during the operating stage and are the stakeholders
who drive the demand. Lastly, Non-Governmental Organizations (NGOs) and the local
community are charitable beneficiaries. NGOs receive environmental assurance from a
BIPV project, but provide no real benefit to the project.
The focal
organization
Problem
Stakeholders
Zoff
[ uni]
n ts taee
wr
Beneficiardes
t Tre v
Figure 23: Stakeholders of a BIPXV project (adapted from Crawley)
During this work representatives from different stakeholders were interviewed: tech BIPV
enterprises, BIPV integrators, developers, investors, building developers, architects,
installers, and early adopters of fagade BIPV systems. The goal of the interviews was to
understand the stakeholders' needs and the value of different attributes of BIPV systems.
In addition, technical challenges were identified.
Figure 24 shows a segmentation of stakeholders that prioritizes them by relative
importance to the focal organization (building with a fagade BIPV system). The basis of
the prioritization is the value that these stakeholders deliver to the project. High-priority
stakeholders must be considered, and their needs must be satisfied; medium-priority
63
stakeholders must be considered, and their needs should be satisfied; lastly, low priority
stakeholders should be considered, and their needs might be satisfied.
Figure 24: Prioritizing stakeholders (adapted from Crawley)
Stakeholders' needs can be classified according to those that provide excitement, those that
provide roughly linear return with performance, and those that are considered essential
(Crawley 2011). Figure 25 depicts the intensity of demand of each stakeholder through the
expanded system. The arrows represent the value flow between two stakeholders. The
color of the arrows indicates the intensity of that value flow, i.e., how important that value
flow is to the stakeholder (need urgency).
Accordingly, red arrows represent stakeholder's inputs that must be provided. Blue arrows
and green arrows correspond to stakeholder's inputs that should be and might be provided,
respectively. For instance, a building must have electricity supply and a system that
separates the interior from the exterior. In addition, buildings should have a fagade that
contributes to conserve energy; the fagade should also contribute to foster the building
aesthetic.
64
A BIPV fagade must have the approval of architects and developers. When designing a
building, the former should consider functional requirements provided by the investor;
however, this is not strictly mandatory because architects should also consider the context
in which the building will be placed and the functions that the building should support
beyond those listed by a specific user.
65
Figure 25: Stakeholder value chain of a BIPV Faeade Project
In addition to showing the value flows and intensity of demand, Figure 25 overlaps how
competition in supply influences these value flows. A red square represents a high level of
supply importance, i.e., the stakeholder providing the input (value flow) is very important
66
and market competition is not significant. Similarly, yellow squares and green squares
indicate medium and low levels of supply importance, respectively.
For example, the BIPV fagade project is not relevant for the building project as a source of
exterior aesthetic, interior functional space (light source), electricity supply, energy
efficiency, or as an object that contributes to separate the interior from the exterior. No
doubt, currently there are many alternatives in the market that can provide the same
functions.
In particular, the energy conversion function is not highly valued because, in a legacy
world, electricity can be economically supplied by the utility. Undoubtedly, the
commercial landscape is challenging, 24 unless the regulator defines a regulatory mandate,
which was represented by a yellow arrow in Figure 25. The regulatory support could either
support the economics of the project (for example, utilizing a tax credit mechanism) or
force the requirement to develop distributed energy generation (for instance, by defining
zero-energy building mandates). The latter makes the functionality of the BIPV system
more important for the building project.
It is also important to remark that BIPV systems will face the principal-agent problem that
has been well identified in the energy efficiency sector, i.e., the owner of the building and
its user may not be the same agent and, consequently, they may have different incentives.
Generally, investors do not have incentives to make an upfront investment in order to
produce long-term operational savings. Thus, the question of who will be the primary
beneficiary of the system is important. Will it be the owner of the building? Will it be the
user of the building? Or will it be both, if they are not the same stakeholder? In this
context, early adoption of fagade BIPV systems will likely be more acceptable for
corporate buildings, museums, and any other buildings where the investor not only has a
long-term commitment, but also is the primary user.
BIPV also are characterized by complex integration as part of the component
characteristic. There are some political aspects as well involved with the constructability of
Particularly in the U.S., where the development of new resources of natural gas has
decreased both electricity prices and carbon emissions.
67
24
BIPV. For example, some regulated markets segment trades, i.e., people are organized in
different structures in order to construct buildings. In this context, it is important to define
whether the product will be either part of the building infrastructure or part of the furniture
of the building, as a product.
68
Chapter 4 - Faeade Building Integrated
Photovoltaics: System Architecture Analysis
Civil architects use a combination of two methods to decompose a fagade system (Knaack,
et al. 2007, 56). The first decomposes the fagade into separate functional elements, and the
second decomposes the fagade into layered elements. In the former, each element has a
separate function, and only when these elements are combined does the fagade system
perform as desired (Figure 26, left). In the latter, all desired functions shall be realized at
any point on the fagade (Figure 26, right).
Figure 26: Decomposition into separate functional elements (left) and layered elements (right)
(Knaack, 2007 p. 56)
The decomposition strategy affects the implementation cost, energy efficiency and the
appearance of the building. The next three figures represent how both the percentage of
glazing surface and the glazing's quality of thermal insulation affect the specific primary
energy demand in a typical office building in central Europe (Knaack, et al. 2007, 70). In
such an environment, if double-glazing and internal size protection were utilized, the civil
architect could suggest the development of a fagade with almost 30% glazing without
compromising the building's energy consumption (Figure 27). However, when the civil
architect suggests the utilization of triple glazing artifacts, the fagade could have almost
69
70% glazing without compromising the primary energy demand of the building (Figure
28). In addition, Figure 29 shows a similar analysis considering the use of triple glazing
plus an external sun protection.
5o0
I
S131%
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Figure 27: Specific annual energy demand of an office building in central Europe
-double glazing (Knaack, et al. 2007, 70)
I
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Figure 28: Specific annual energy demand of an office building in central Europe
-triple glazing (Knaack, et al. 2007, 70)
70
100%
infaale
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Figure 29: Specific annual energy demand of an office building in central Europe
-triple
glazing & external sun protection (Knaack, et al. 2007, 70)
By applying functional tradeoffs in different sections of the fagade, the civil architect
might decide to install elements with higher thermal insulation, but lower transparency
(i.e., opaque surface), not necessary compromising the building aesthetic.
Regarding the implementation of fagade BIPV systems, on the one hand, by following the
method of decomposition into separate functional elements, the architect can plan to install
opaque FPVAs in a defined area of the fagade, and other types of fagade artifacts - either
transparent or opaque -
that do not generate electricity in other areas of the building
fagade. This method allows higher modularization and, consequently, a more specific
allocation of functions.
On the other hand, the architect can decompose the system into layered elements, where
similar functions are provided along a section of the building fagade. This approach would
be related to the integration of either semitransparent or transparent FPVAs because both
the light transmission function (i.e., transparency
characteristic) and the energy
transformation function are integrated into the same section of the fagade.
71
4.1
System Architecture Analysis - Artifact Level
Analyzing the architecture of different FPVAs requires decomposing the system into
functional elements, documenting the interactions between the elements, and clustering the
elements into chunks. There are different types of interactions that should be analyzed:
spatial, energy, etc. Additionally, different categories of complexities must be understood:
1) behavioral complexity, 2) interface complexity, and 3) structural complexity. In this
context, it is important to highlight that civil architects prefer to adopt simple products,
with low complexity.
According to Suh's theory (Suh 1998), the system architect must understand the
underlying relations between functional requirements, design parameters and process
values. As Suh emphasizes, design is an iterative process in which the dependencies are
defined. Well-defined system architecture should include a hierarchical functional
decomposition starting from the solution-neutral function moving down to the system-level
functions to sub-system-level functions. The system architect must identify the objects
-
and their attributes - that will be transformed, transmitted, resisted, redirected, or other.
As exemplified in this work, early in the design phase the system architect and the
customer are confronted with strategic architectural choices that only the client should
make: should the FPVA have the multipurpose of transmitting and transforming light, or
should it have a single purpose? Depending on the choice, the architecture of the system
takes different forms (Rechtin 1990, 69). Rechtin emphasizes that a single purpose system
can be more efficient for its specified function. As presented in Section 3.2.2.1 and Figure
20, single-purpose FPVAs are naturally more efficient than light-through FPVAs.
The architect of the system must also understand the importance of elegance and convey
the architecture of the system in simple, elegant terms. Elegance in system architecting
entails a broad concept that is related not only to the arrangement of form and function, but
also to the acceptance of the system's appearance and the harmony in the process of
architecting by which the architect achieves the approval of the project, satisfying
stakeholders' needs.
72
When designing systems that are strongly influenced by perceptions of people, the
architect should consider the aesthetic of design. As indicated by the architect and
industrial designer David Pye, "there are two questions which concern every designer.
First: if some things are of 'good' appearance while others are not, why are the 'good' ones
good and 'bad' ones bad? What causes the difference? Second: supposing that they are
good, who is the better for it? Does it really matter? If so, why?" (Pye 1995, 96). These
questions are related not only to aesthetics, but also to the value that the system provides.
In general, early-stage technology concepts attempting to satisfy emerging markets have
not well defined priorities, in partly because the market needs and functions to be
performed are uncertain. In this context, even though different emerging architectural
concepts can have valued attributes, the comparison of system architectures based on
valued attributes might not provide the best insight at this stage; it might be preferable to
compare architecture drawbacks. As stated by Rechtin, "the choice between architectures
may well depend upon which set of drawbacks the client can handle best" (Rechtin 1990,
95).
Glazed building fagades could be considered as interfaces. From the systems architecture
perspective, an interface should have a compatible structural relationship to perform its
function (Crawley 2011 b). For example, three functions of glazed building fagades are:
separating the ambient, reducing heat transfer, and transmitting light. All these functions
are performed in the boundary of the larger system in which the fagade is embedded - the
building. In addition, the interface's processes (separating, reducing and transmitting) act
over the same objects on both sides of the system boundaries (ambient, heat transfer and
light, respectively).
The next sections analyze three families of FPVAs that would likely be used in fagade
BIPV. The aim is to synthesize the needs of the beneficiaries, the goals of performance, the
function process, and the form structure.
4.1.1
Opaque BIPV Faeade Systems
Figure 30 shows the needs of direct and indirect users of an opaque fagade BIPV system,
assuming that the system has been installed. The left side of the figure presents the need of
73
stakeholders that interact with the fagade outside the building. In such a use context,
stakeholders can be influenced by the aesthetic characteristic of the BIPV fagade system
and the building as a whole. On the other hand, the right side of the figure presents the
needs of stakeholders in the building. In this use context, the needs of stakeholders are
different: they will likely have structural needs, energy consumption needs, regulatory or
sustainability goals to comply with, and, eventually, an aesthetic need (e.g., aesthetic
interior panel and natural light, which shall be provided by another system because the
fagade system as a whole will be decomposed in different functional elements).
Product/system boundary
USE CONTEXT
OUTDOOR
I
Need
Goal
INDOOR
,
Ambient
Function & Form
Figure 30: Opaque BIPV Faeade Systems -
Goal
Need
Interface analysis
Figure 30 also summarizes different goals: reducing the building's energy needs (thermal
and cooling loads); powering electricity needs in the building; separate building space; and
inspiring people's vision in two different use contexts (indoor and outdoor). The opaque
BIPV fagade system is the instrument -
element of form -
that performs these functions
by separating the ambient, insulating heat, and converting and reflecting light. The blue
74
lines in Figure 30 indicate the relation between different processes and needs in order to
illustrate the value creation process (i.e., how a function intersects with stakeholders'
needs). Users inside the building cannot perceive the aesthetics of the BIPV system
because the outer opaque panel of the BIPV fagade system performs the light conversion
and reflection process and does not transmit light (as described in Figure 14).
In addition, Figure 30 illustrates the duality between facts and perceptions that stresses the
development of sociotechnical systems. On one hand, users (e.g., building managers)
might be able to quantitatively assess how the BIPV system contributes to achieve a
sustainability or policy goal -
if they have been defined. On the other hand, in particular
in those cultural environments where sustainability values are highly appreciated, users
might be inspired by the idea of the energy insulation and conversion processes; in so
doing, the system can influence people's perceptions regarding the commitment of
sustainability or policy goals, creating excitement about the function of the system.
However, there might be asymmetries of information about the system's ability to reduce
the building's energy expenses or comply with either a sustainability or regulatory goal.
Technically, there are no unresolved tensions between processes -
the system does not
have conflicting goals influencing the same object. However, as value entails benefit at
competitive cost, questions regarding the importance of the system in reference to needs of
stakeholders are important: Do stakeholders have to comply with either regulatory or
sustainability goals that incentivize them to look for a BIPV fagade solution? Do
stakeholders need to have a local source of electricity to power their needs? Is the system
easy to integrate or replace in existing buildings or it can only be smoothly integrated in
new buildings? Does the photovoltaic function of the system contribute to reduce energy
expenses? What would be the cost of the system? How should cost be distributed between
the different functions of the system?
Figure 31 synthesizes the system architecture analysis using the axiomatic design
framework developed by Suh (Suh 1998, Meyer 2007). Four high-level functional
requirements were defined, two of which decomposed into a second level. In addition, the
figure presents the design parameters, and the dependencies between functional
75
requirements and design parameters. Colors red, blue and yellow represent the
characteristic of the dependencies: high, medium or low respectively.
1
FR 1.1: Transmit Light to the PV System
FR1: Transform Energy
2
FR 1.2: Transform Light into Electricity
3 FR2: Insulate Heat
4 FR3: Defines the Interior Wall
E6FR4I: Influence Aesthetic
F
.:Etro
Figure 31: Opaque BIPV Faeade Systems - Map of Functional Requirements and Design Parameters
If the aesthetic requirements are not considered, functional requirements could be defined
in a solution-neutral environment, i.e., the number of functional requirements matches the
number of design parameters (Figure 31, square highlighted in green shows the initial
boundaries of the system). Heat insulation (FR2), which is influenced by DPI, DP2. DP3,
and DP4, is the only coupled functional requirement.
The heat insulation characteristic is critical when the comfortable temperature range inside
the building is different from the ambient temperature range outside the building. As also
indicated in the previous chapter, the first goal of near-zero energy consumption building
will be energy efficiency; therefore, the photovoltaic characteristic of the building fagade
shall not sacrifice the thermal performance of the fagade.
In order to simplify the complexity of the system, in particular, the coupled relation
between FR2, FR3 and DP4, the system architect can define design rules, for instance, he
could define the attributes of DP4 early in the design process. The concept of design rules
has been highly documented (Baldwin and Clark 2000, 64-70).
76
When the aesthetic functional requirement is considered, in order to maintain the
independency of functional requirements in the interior side of the BIPV artifact (FR4. 1), a
new design parameter should be considered: the interior panel cover (DP5). Nevertheless,
the functional requirements are not defined in a solution-neutral environment because the
25
number of functional requirements is greater than that of design parameters, i.e., the
design is coupled.
In this context, the system architect needs to resolve the aesthetic vs. function tension:
should function follow form or should form follow function? This question is particularly
interesting regarding the relation between the energy transformation function (FRI) and
the exterior aesthetic function (FR4.2).
Do the users -
indicated on the left side of Figure 27 - really perceive the detailed form
attributes of FPVAs once they are installed? Generally, users do not pay attention to the
detailed attributes2 6 of fagade sections outside the building, in particular, when the fagade
sections are far from the areas that users can access (e.g., higher parts of the building).
Given that scenario, the exterior aesthetic characteristic of the FPVA might not be an
important driving factor of the fagade BIPV system as a whole. Without affecting
functionality, FPVAs can be designed in a solution-neutral environment by defining a
design rule for the form of the system (i.e., FR4.2 in Figure 31).
4.1.2
Semi-transparent Systems
Figure 32 shows the needs of three groups of stakeholders. As explained in Section 3.3.2,
three types of semitransparent fagade BIPV were studied in this work: spaced crystalline
systems, solar-reflector concentrator systems, and semitransparent systems.
In this case, a semi-transparent FPVA has the ability to convert (transform), transmit and
reflect light2 7 (compared with the opaque system, it has one additional function). As the
amount of incident light is limited, the system architect will have to balance the trade-off
Six functional requirements and five design parameters.
26 Form characteristics that can only be perceived when people closely observe the object.
27 Although the system should minimize reflection in order to maximize the transformation
and transmission functions.
77
25
between the system's ability to transmit and the system's ability to transform light;
therefore, a multi-beneficiary approach is required. This multi-beneficiary approach should
consider the stakeholders' needs in different use contexts and the burden that some legacy
systems 28 that interact with the semitransparent FPVA impose on the system. The tension
between transparency and energy transformation represents an important sociotechnical
challenge for the development and adoption of semitransparent FPVAs.
The left side of Figure 32 presents the needs of stakeholders that interact with the fagade
outside the building. In such a use context, stakeholders are influenced by the aesthetic
characteristics of the BIPV fagade system and the building as a whole. On the other hand,
the right section of the figure presents the needs of stakeholders that directly benefit or use
the BIPV fagade system inside the building. These needs were also described in the
previous section.
The transparency attribute of FPVAs enhances the interface functionality of the building
fagade, particularly, if the system is installed in locations that users can frequently and
closely appreciate. In addition, users can perceive the form of the system from both sides
of the building (outside/inside); therefore, a compatible structural relationship is required.
This compatibility means that the system's attribute of form should fit with two use
contexts: inside and outside the building. However, as both use contexts are different, such
a compatible structural relationship might be difficult to achieve not only from the
technological design perspective (the design of the artifact), but also from the perspective
of civil architects, who integrate the artifact in the building.
In the next three subsections, the three main families of semitransparent systems are
analyzed: 1) spaced crystalline panels, 2) solar reflector concentrator with crystalline
panels, and 3) semitransparent panels.
28
E.g., the integration of the balance of system with the building's electricity system.
78
Product/system boundary
USE CONTEXT
OUTDOOR
I
It
Compatible
Interface
Need
Goal
Function & Form
Goal
Need
Figure 32: Semitransparent BIPV Faeade Systems - Interface analysis
Architecture Analysis - Spaced Crystalline Panel
Figure 33 synthesizes the system architecture analysis using the axiomatic design
framework developed by Suh (Suh
1998). Four technical high-level functional
requirements were defined. In addition, a fifth functional requirement (FR5) represents the
aesthetic function of the system.
The figure also presents the design parameters, and the dependencies between functional
requirements and design parameters.
Colors red, blue and yellow represent the
characteristic of the dependency: high, medium or low, respectively.
If only technical characteristics are considered, functional requirements could be defined in
a solution-neutral environment because the number of functional requirement equals the
number of design parameters (highlighted by a green box in Figure 33). However, in this
case the function of light transmission and light transformation are coupled. The
79
transmission of light will depend on the number and size of crystalline cells in the panel.
As the PV System (DP2) is an opaque photovoltaic system, the characteristics of the light
transmitted will depend on the distribution of crystalline cells in the panel and the
properties of the light-through artifacts (DPI and DP4). Accordingly, the dependency
between FR4 and DP2 is characterized as medium (blue color, Figure 33) because the light
is transmitted to the interior through the space between cells, not through the cells itself.
The heat insulation characteristic depends on the characteristics of all the components that
conform the panel (DPl-4), i.e., different elements of form (design parameters) are
instruments of the same process (resist heat transfer). In order to simplify the complexity
of the system, the system architect can define design rules; for instance, he could define the
attributes of DP4 so as to eliminate the coupled loop between DP3, FR3, and FR4. The
concept of design rules has been highly documented (Baldwin and Clark 2000).
S
S
CC
1
FR 1: Transmit Light to the PV System
2
FR 2: Transform Light Into Electricity
3
FR3:
4
FR4: Transmit Light to the Interior
Insulate Heat
6
FR 5.1: Interior
FRS: Influence Aesthetic
7
FR 5.2: Exterior
Figure 33: Spaced Crystalline Panel
-
Map of Functional Requirements and Design Parameters
When the aesthetic characteristic is considered, the system design becomes more coupled.
The adoption of spaced crystalline panel would be more difficult than that of opaque BIPV
fagade systems not only because the aesthetic characteristics are highly coupled with
technical functions, but also because the system's aesthetic is directly associated with
80
architects' and users' preferences, which are highly influenced by the use context.
Therefore, as acceptance of the form of the system is highly context dependent, it will be
difficult to define FR5 as solution-neutral requirement. The system architect shall recall
that good requirements are necessary, verifiable and attainable.
From the exterior of the building, users might not be closely exposed to the installed BIPV
system; it will be just too high and too far for users to perceive the details of the system's
form attributes. However, from the interior of the building, users will not only be exposed
to the panel's form attributes, but also to the light that the system projects and to the
shadow that is projected onto the interior of the building (Figure 34). All these form
aspects should be compatible with the use context inside the building where the system is
installed.
Figure 34: Spaced Crystalline BIPV Panel - Source: Renewable energy focus (left). EnergyGlass (Right)
Civil architects might be willing to use spaced crystalline FPVAs within a broader
objective, beyond pure functionality, when the fagade contributes to leisure or learning
contexts; where users would be able to appreciate styling (Meyer 2007, 91). However, a
regulatory or sustainability incentive shall drive the need, as much as economic
performance; otherwise, civil architects could have reached the desired styling only by
leveraging the glass's form, without requiring photovoltaic systems embedded in the
fagade.
81
Architecture Analysis - Solar Reflector Concentrator with Crystalline Panels
Solar reflector concentrator systems have a different architecture from that analyzed in the
previous section. The light-reflection function redirects electromagnetic energy to allow its
transformation in other section of the fagade system. The system architect changes the
position and orientation of crystalline solar cells to diminish the light obstruction and
leverage the system's ability to allow views to inside and outside (Figure 35).
Outside
14
Inside
111
------------
PV(e|
Air/Argon
1a
VSIBLE--
1
12
Figure 35: Solar reflector concentrator concept. Pythagoras Solar (Left), Tropiglas (Right)
There are two main technical trade-offs. First, the system architect needs to decide what
fraction of the electromagnetic energy would be redirected to the photovoltaic system. The
more the system redirects light, the less the system allows interior and exterior views. In
addition, the system architect must define where the electromagnetic energy will be
transformed to electric energy -
i.e., where the photovoltaic systems will be located. The
further the photovoltaic system is from the point where the light is redirected, the greater
the dispersed energy that cannot be transformed -
i.e., redirected energy lost. These trade-
offs not only influence the technical performance of the system, but also affect the user's
perceptions because they directly impact the aesthetic of the fagade system.
According to Crawley (2011 d), "functionality drives complexity in any given concept.
Essential complexity is that which is essential to deliver functionality before gratuitous
complexity slips in... the performance level for a given functionality will also drive more
82
complexity into a system. Consequently, functionality and performance drive essential
complexity for any given concept."
Figure 36 illustrates two solar reflector concentrator systems that use crystalline cells. On
the one hand (left figure), the energy is transformed close to the section where light is
reflected and many crystalline cells (placed horizontally) are utilized along the panel. On
the other hand (right), even though the light is reflected along the glass structure, the light
is transformed only in the frame of the panel, where the crystalline PV cells are located. In
this context, the system developed by Pythagoras Solar (left) shows its actual complexity,
i.e., users can appreciate the complexity of the system architecture. In addition, because of
the fact that the system transmits distorted light, the perceived complexity is higher than
the actual complexity -
if the aesthetic function is important, high perceived complexity
may constrain the market adoption of the system.29 In contrast, the system developed by
Invisergy (right) hides its actual complexity; therefore, the system's perceived complexity
is lower than the actual complexity of the system.
Both Pythagoras Solar and Invisergy use the light reflector concentrator concept to
transform electromagnetic energy. However, the performance efficiency per meter square -
energy conversion
of the system developed by Pythagoras Solar triples that of
Invisergy. The comparison of both design concepts shows how performance drives
essential complexity for a given concept (Figure 37). Nevertheless, whereas Pythagoras
Solar has increased the system performance by an approximate factor of three, the actual
complexity of the system has been increased by a higher factor (which depends on the
number of parts, type of parts, connections and types of connections).
Complexity can be also reflected in the product's specification sheets. For instance, in
the Pythagoras Solar case, architects may find it difficult to understand the emergence of
the system in terms of solar heat gain, visual light and UV transmittance. (Source:
http://www.pythagoras-solar.com/wp-content/uploads/2012/04/TechSpec.pdf)
29
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r I.- GM o Md4Gc ) -
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83
Figure 36: Solar reflector concentrator with crystalline cells. Source: Pythagoras Solar (left30 ), Invisergy (right)
L
E
0
The perceived complexity is
higher than the actual complexity
because of the system's
emergence (distorted light)
E
Perceivd Complexty
Actual Complexity
Essential Complexity
a)
W,
Factor >> 3
Difference
driven by the
system's
performance
Actual Complexity
Essential Complexity
Perds9&Gnplkt
Concept A:
Invisergy
Factor = 3 - 4
Concept B:
Pythagoras Solar
Specific
Power Density
KW/m2
Figure 37: Qualitative comparison of the system's complexity
This case has illustrated that both functionality and performance drive essential complexity
for any given concept. During the system architecting and concept selection processes,
Crawley recommends to prefer concepts with low essential complexity and the ability to
30
Source:
http://www.jetsongreen.com/2011/03/pythagoras-solar-photovoltaic-window-
unit.html (Accessed September 2012)
84
absorb rises in functionality and performance with modest increases in essential
complexity (Crawley 2011 d).
Figure 38 synthesizes the system architecture analysis using the axiomatic design
framework developed by Suh (Suh 1998). Five technical high-level
functional
requirements were defined. The figure also presents five design parameters, and the
dependencies between functional requirements and design parameters. Colors red, blue and
yellow represent the characteristic of the dependency: high, medium or low, respectively.
In Figure 38, some instruments share the same process. For example, the process of
transmitting (light) is shared by the glass panels, the generation module, and the thermal
insulation module (DP 1 - 4). In addition, light is a shared object (operand) by three
processes (transmission, reflection, and conversion).
Finally, Figure 38 shows two coupled outcomes. On the one hand, the function of light
reflection and transmission (FR2) is coupled with the function of energy transformation
(FR3). On the other hand, the function of heat insulation (FR4) and light transmission
(FR5) are also coupled.
If only technical characteristics were considered, functional requirements could have been
defined in a solution-neutral environment because the number of functional requirements
equals the number of design parameters (highlighted by a green box in Figure 38).
However, when aesthetic requirements are considered, they directly influence the function
of the system.
The exterior aesthetic characteristic of the FPVA may not appear to be a driving factor of
the fagade BIPV system as a whole. However, from the interior side of the building, users
will not only be exposed to the form attributes of the panel, but also to the light that the
system projects into the interior of the building (Figure 36). These form aspects should be
compatible with the user preferences and the use context inside the building where the
system is installed. The architect should wonder whether system performance is important
enough to sacrifice form, and if so, in which context it should be sacrificed.
85
1
FR 1: Transmit Light to the Generation Module
2
FR 2: Reflect & Transmit Light
3
FR 3: Transform Light Into Electricity
4
FR 4: Insulate Heat
S
FR5: Transmit Light to the Interior
6
FR 5.1: Interior
FR6: Influence Aesthetic
7
FR 5.2: Exterior
Figure 38: Solar reflector concentrator with crystalline cells
-
Map of Functional Requirements and Design
Parameters
Architecture Analysis - Semitransparent Panels
This architecture uses a semitransparent PV thin layer assembled onto the glass. As
opposed to spaced crystalline panels, in semitransparent panels the dependency between
the light transmission function and the PV System (DP2) is high (red color, Figure 39)
because the PV system itself is a semitransparent element.
The semitransparent PV module has higher technical risk and complexity because it
performs a higher number of functions, i.e., simultaneously transmit and transform light.
According to Baldwin and Clark (Baldwin and Clark 2000, 221-285) the variance of the
module's value increases linearly with the module's number of tasks, although a higher
86
value might be expected if during the design and experimentation processes, the designer
filters or controls the negative outcomes, leaving only the upside potential.
E1
t
I
1
FR 1: Transmit Light to the PV System
2
FR 2: Transform Light into Electricity
3
FR 3: Insulate Heat
5
FR 4: Transmit Light from exterior to interior
CC
FR 5.1: Interior
6
FR5: influence Aesthetic
FR 5.2: Exterior
7
Figure 39: Semi-transparent BIPV Panel
-
Map of Functional Requirements and Design Parameters
As mentioned before, civil architects might be willing to use semitransparent FPVAs
within a broader objective, beyond pure functionality, when the fagade contributes to
leisure or learning contexts, i.e., where users would be able to appreciate styling (Meyer
2007, 91). The desired attribute of transparency and color might be highly influenced by
user's needs and the environmental context where the system will be installed (Figure 40
and Figure 41). Therefore, this product will likely be customer - and site - specific. These
downstream influences challenge the commercialization of semitransparent FPVA from
the perspective of the manufacturing and supply chain processes by requiring high
flexibility.
87
Figure 40: Application of Semi-transparent BIPV Panel (Source: Schott Solar)
Figure 41: Application of Semi-transparent BIPV panels by degree of transparency: 5% (left), 15% (center), 25%
(right). (Source: Schfico Faeade Modules)
4.1.3
Transparent Systems
The electromagnetic energy can be decomposed in two, uncoupled spectrums: visible and
infrared -
invisible. Transparent BIPV systems utilize this principle with the intent to
transform only the light's invisible spectrum into electric energy. In so doing, transparent
BIPV systems resolve the technical tension described in the previous section 88
transforming vs. transmitting light -
in particular, the friction between facts and
perceptions that characterizes sociotechnical systems. Although the energy transformation
capability is limited by the energy contained in this portion of the light spectrum (Section
3.2.2.1) and the efficiency of the panel.
Figure 42 illustrates the needs, goals and processes that entail the insertion of a transparent
FPVA into a building fagade. It shows how the light transmission function is uncoupled
from the light transformation function. In addition, as has been shown before, the blue
lines represent the value flow (from instrument's function to goals and stakeholder's
needs).
Product/system boundary
OUTDOOR
USE CONTEXT
.
I
INDOOR
Compatible
Interface
Need
Goal
L
1
Function & Form
Figure 42: Transparent BIPV Faeade Systems -
89
Goal
Interface analysis
Need
This architecture uses a transparent glass coating -
PV thin layer.
As opposed to
semitransparent panels, transparent panels have a low dependency between the light
transmission function and the PV System, DP2 (yellow color, Figure 43) because the PV
system only intends to transform the infrared spectrum of the light. Consequently, this
architecture gives design-aesthetic freedom.
The influence of the aesthetics of the building will only depend on the outer and inner
glasses (DPI and DP4). The heat insulation function is coupled, i.e., it depends on the
attributes of the four design parameters that were defined. The PV System (DP2)
influences the heat insulation function because, by transforming the infrared spectrum to
electricity, it resists the transfer of infrared energy into the building.
48
C
1
FR 1: Transmit Light to the PV System
2
FR 2: Transform Light into Electricity
3
FR13: Insulate Heat
5
FR4I: Transmit Light to the Interior
I
FR 5.1: Interior
6
-FRS:
Influence Aesthetic
FRt 5.2: Exterior
7
Figure 43: Transparent Panel -
4.1.4
Map of Functional Requirements and Design Parameters
Summary of the Systems Architecture Analysis
In the previous sections, different system architectures for FPVAs were analyzed. As the
technology is in an emerging phase and the markets needs are not clearly defined, it is
3
This is a novel technology. The concept is being developed by some startups, e.g.,
Ubiquitous Energy and Solarmer.
90
difficult to compare the architectures based on the value that they provide. In contrast, I
have highlighted some architectural drawbacks, particularly, the conceptual complexity
associated with the resolution of technical tensions and the downstream influences of the
aesthetic function in different use contexts. In some cases, the analysis has shown that the
aesthetic function is coupled with the technical function in the circumstances that aesthetic
requirements can significantly affect the energy generation function.
In this context, the different FPVA architectures can be classified in three groups:
uncoupled designs, decoupled designs, and coupled designs. Based on the system
architecture analysis, the latter can have two levels of complexities, i.e., both the solar
reflector concentrator systems and the semitransparent systems are coupled designs, but
the former entails an additional process and several additional parts.
Figure 44 qualitatively shows the relation between the level of complexity and the electric
power density that different FPVA architectures have currently achieved. On the one hand,
the opaque FPVA -
uncoupled design -
has not only the lowest level of complexity but
also the highest technical performance metric (electric power density). On the other hand,
the solar reflector concentrator architecture has the highest complexity and, as presented in
the previous section, the system complexity can significantly change according to the
system's performance: the higher the performance, the higher the complexity, and vice
versa.
91
J
EI
0.
0
DECOUPLED DESIGN
I
I
Electric Power Density
Spaced Crystalline Solar Cels
System Concept Evaluation
Figure 44: Energy transformation performance and system complexity-comparison between different concepts32
Figure 45 synthesizes the analysis by considering the system's degree of complexity and
the level of subjective stakeholder judgment, in addition to the electric power density.
Neither visible transparent polymer cells nor low performance solar reflector concentrator
systems influence the building aesthetic, as opposed to opaque PV systems that only
influence the exterior building aesthetic. It can be appreciated that the adoption of
semitransparent or light-through systems entails a high level of subjective stakeholder
judgment because the system influences both the indoor and the outdoor building aesthetic;
therefore, in order to project harmony beyond the system's boundaries, the use context
should be considered in order to create compatible designs.
Visible transparent polymer solar cell architecture has been classified as coupled because
currently the system has not achieved high quality transparency. However, the ideal is to
work towards that direction.
92
32
Opaque System
Transparent System
Light-through System
Intend to Influence the Building Aesthetic -INDOOR
NO
NO
YES
Intend to Influence the Building Aesthetic -OUTDOOR
YES
YES
NO
'I
In-Glass Spaced
Ciystalline
C
solar CONlS
High
Medium
Low
Degree of functional connectivity (function & form) and subjective stakeholder judgment
Figure 45: Energy transformation performance, system complexity, and perceived complexity-comparison
between different concepts
4.2
Implication for Market Adoption: Dominant Design
Future directions of emerging technologies are unknowable; therefore, success in
revolutionary systems is commonly not found where the original concept suggested it
would be (Christensen 2011, 178) (Maier and Rechtin 2009, 71). In this context, an
assessment of a disruptive technology involves an understanding of its advantages in
meeting user needs and an assessment of the nature of the industry that is likely to develop
around a relevant product innovation.
Why does the system's architecture complexity matter in the analysis of novel, early-stage
solutions attempting to lead a paradigm shift in the integration of photovoltaic technology
in buildings?
As Baldwin and Clark emphasize, "the larger task structures, which correspond to more
complex system designs, have a more upside and downside potential than their smaller and
simpler counterparts. However, large, complex modules are also more expensive to create,
93
test, and integrate than small ones, and one must balance their economic potential against
these costs and the risk of failure" (Baldwin and Clark 2000, 255). They add that "neither
modular designs nor interdependent designs are inherently superior: the costs and benefits
of each approach vary by case and over time" (Baldwin and Clark 2000, 258).
In the context of BIPV systems, when the system demands a higher level of subjective
judgment by stakeholders, system requirements will likely be heterogeneous and at higher
level of customization. This type of judgment intensifies the separation between the
customers, who have the information about needs and preferences, and the manufacturers,
who have the solution information. This separation makes the experimentation and
adoption of products more difficult and less frequent, so too the capability to improve
products (Thomke 2003, 241-272). The more inferior the capability to run market
experiments, the lower the probability to transform the concept in a dominant architecture.
As Thomke emphasizes, "when companies have to work with hundreds of customers with
different needs, each requiring market research and a well managed interactive process, it
is easy to see how the companies can become overwhelmed and thus focus only on the
largest and most profitable customers" (Thomke 2003, 244). In the case of semitransparent
FPVAs, which are highly influenced by their use context and surrounding environment, it
could be difficult to define highly standardized products or find large customers.
Therefore, manufacturing and supply chain processes will require flexibility.
Along these lines, James McNerney et al. (McNerney, et al. 2011) emphasize that
technology performance depends not only on cumulative production, but also on the design
complexity, which can be determined from the design structure matrix -
following a
similar methodology shown in this chapter. McNerney et al. conclude that one could
potentially analyze the DSMs of different technologies and compute their corresponding
design complexity. In their model, complexity is analyzed based on two factors: the design
complexity itself and the intrinsic difficulty of improving individual components.
In the case of a BIPV system, this study shows that the adoption will be constrained not
only by the complexity of the product itself, but also by the visibility of the system, i.e.,
how users perceive the aesthetic function of the system in the use context and whether or
94
not the aesthetic function is an important factor to consider. Therefore, the system's
harmony and simplicity not only need to be conceptualized in at the component level, but
also need to be considered based on how the component is inserted into the larger system
in which it will be embedded.
It is important to note that crystalline cells and thin film technologies are currently widely
adopted for the development of large PV solar plants and rooftop solar systems. Therefore,
by sharing systems and processes across different products and markets, manufacturers can
use these photovoltaic systems as a platform for the development of opaque BIPV systems.
In the near term, because the experience obtained from mass market can be easily
leveraged in niche BIPV markets, the commonality effect may have also profound
implications in terms of the competitive advantage that opaque BIPV systems have over
other systems studied in this thesis.
Undoubtedly, the context in which people live is evolving in sociocultural and technical
terms. This evolution will likely affect not only how people use energy in buildings, but
also how the electricity is produced and supplied to customers. As BIPV systems are
integrated into buildings and closely interact with people, novel designs that integrate
needs, technology and language have emerged in niche markets. These new designs also
attempt to anticipate an emerging need for near-zero energy consumption buildings that
will likely be driven by regulation by the end of this decade.
However, design-inspired innovation does not necessarily imply the design of aesthetic
products, but rather it requires a profound understanding of values and meanings. Verganti
emphasizes: "if the product is meaningful, there is no need to overburden it with powerful
functionality" (Verganti 2009, 93).
In the context of BIPV fagade systems, it is important to understand what functionalities
are needed, and whether an elegant solution can be achieved by modularization, i.e.,
allocating functions to different sections of the building. This study has illustrated that
semi-transparent light-through systems not only are exposed to architects' and users' nontechnical judgment, but also, as compared to the performance provided by either a
modularized solution using single purpose systems or a transparent BIPV system, semi95
transparent light-through systems overburden the functionality of a given section of the
fagade at expense of both visibility and electricity generation performance.
96
Chapter 5 - Conclusions
David Nye, in his book Electrifying America indicates: "from the start, home
electrification was not merely utilitarian. The novelty of the new force encouraged
experimentation, and people took pleasure in festooning their homes and gardens with
light, not in order to see better, but to see their possessions anew" (Nye 1992, 245). In
addition, Utterback has reinforced the concept of design-inspired innovation arguing that
recent "evidence shows that we are indeed coming (returning?) to innovation inspired by
design that truly delights the user" (Utterback, Vedin, et al. 2006, 227).
Worldwide energy consumption will likely triple by the end of this century. Innovation
within the energy industry is required so as to decrease greenhouse emissions. However,
historically, energy transitions have taken approximately five decades.
There are significant opportunities to improve the efficiency of energy use in buildings.
Particularly in the United States, 41% of primary energy consumption in 2010 went into
buildings. This need for improvement in buildings' energy consumption opens a
remarkable opportunity for innovation over the next two decades.
In this context, it is important to consider the differences that distinguish innovation in the
manufacturing industry from innovation in construction industry, where, as identified by
Slaughter (Slaughter 1998), most reliable testing results are obtained from full-scale
prototypes; components are assembled on-site because of the large scale of the facility;
interactions with the constructed facility are not completely characterized because of the
longevity of use, the unconstrained type of users and uses, and the interaction with the
environment itself; and design, construction, operation, and decommissioning activities are
constrained by codes and regulations.
Building integrated photovoltaic (BIPV) systems have been recently implemented in niche
markets, mainly driven by government incentives along with the anticipated willingness to
elegantly demonstrate the concept of zero-energy buildings. Currently there are several
innovational endeavors in both the component and the product architectural dimensions.
97
This diversity and lack of a dominant architecture characterizes an industry in a Fluid
Phase (details in Table 1, page 27).
This work has applied a broad perspective that combines management, technology, and
social sciences to analyze the development and integration challenges of an emerging,
novel product. It identifies some sociotechnical complexities related to the adoption of
various BIPV systems that would likely be integrated into building fagades as part of a
portfolio of alternatives that might contribute to the development of zero-energy buildings.
The analysis contributes to characterize different products' architectures based on their
technical performance, technical complexity, perceived complexity, and exposure to
subjective judgments. The latter is particularly relevant, because FPVAs will be integrated
in building fagades, which are systems that contribute to communicate purpose and create
context by influencing the space in and around buildings.
Utilizing the axiomatic design method, FPVAs were classified in three groups according to
their architectural complexity: uncoupled designs, decoupled designs, and coupled designs.
As the technology is in an emerging phase and the market needs are not clearly defined, it
is difficult to compare the architectures based on the value that they provide. In contrast,
some architectural drawbacks were highlighted; particularly, the conceptual complexity
associated with the resolution of technical tensions and the downstream influences of the
aesthetic function. In some cases, the analysis has shown that the aesthetic function is
highly coupled with the technical function in the circumstances that aesthetic requirements
(form) can significantly affect the electricity generation function. Therefore, the resolution
of the friction between the aesthetic and the electricity generation function is one of the
early-stage design decisions that influence the adoption of the system.
Opaque FPVA -
uncoupled design - has not only the lowest level of complexity but also
the highest technical performance metric (electric power density). It is important to note
that crystalline cells and thin film technologies are currently widely adopted for the
development of large PV solar plants and rooftop solar systems. Therefore, by sharing
systems and processes across different products and markets, manufacturers can use these
photovoltaic technologies as a platform for the development of opaque BIPV systems. In
the near term, because the experience obtained from mass market can be easily leveraged
98
in niche BIPV markets, the commonality effect may have profound implications in the
competitive advantage that opaque BIPV systems have over other systems that were
analyzed in this work.
The solar reflector concentrator based on prisms and crystalline cells architecture offers a
good balance between power density and transparency. In addition, it utilizes components
that currently are widely developed. However, because the system transmits distorted light,
the perceived complexity is higher than the actual complexity of the system. In this
context, a high perceived complexity may constrain the market adoption of the system.
The adoption of semitransparent or light-through systems entails a high level of subjective
stakeholder judgment because the system influences both the indoor and the outdoor
building aesthetic. Civil architects may be willing to use semitransparent BIPV systems
within a broader objective, beyond pure functionality, when the fagade contributes to
leisure or learning contexts. However, a regulatory or sustainability incentive shall drive
the need, as much as economic performance; otherwise, civil architects could have reached
the desired styling only by leveraging the glass's form, without requiring photovoltaic
systems embedded in the fagade. This product will likely be customer- and site-specific.
Downstream influences may challenge the commercialization of semitransparent FPVAs
from the perspective of the manufacturing and supply chain processes by requiring high
flexibility.
Transparent FPVAs uncouple the aesthetic and electricity generation function. They are
still in the early stage of development. As these systems intend to transform IR light, their
energy density will be limited. In addition, these systems, as well as the other systems
analyzed, influence the heat insulation function resisting the transfer of infrared energy
into the building. However, the lower the energy density, the higher the direct and indirect
costs (in terms of $/W) associated with the installation of BIPV systems.
It has been illustrated that single purpose FPVAs not only result in more control over the
design and adoption of the end system, but also, currently, present the highest performance
in terms of the electricity generation function. It may be too early to show whether single
purpose FPVAs will result in a more expensive system than multipurpose FPVAs.
99
However, because of the changes that the photovoltaic industry has experienced, systems
based on crystalline or thin film solar cells that currently are widely adopted in the market
have a better economic outline than elements that are currently not widely commercialized.
In addition, it is not evident how multipurpose FPVA could share costs into different
functions. In the case of systems with low energy transformation efficiency, it is not
evident that a multipurpose BIPV will cost less overall (in terms of $/kW). In this context,
in light-through systems, form - aesthetic and indoor light quantity and quality - and
technicalperformance - electricity generation - are intrinsically coupled functions where
one function is provided at the expense of the other. If form matters, then the electricity
generation function may not be the primary source of value of the system. If that is the
case, then the question of why should someone develop a complex single-purpose
supporting system - e.g., the balance of system - to support a function that might not be
the artifact's primary source of value may be relevant, particularly if the cost of the balance
of system (in terms of $/kW) is comparable to the cost of the PV system. In this context,
electric interconnection between the BIPV system and the existing electricity system may
overburden the design of BIPV systems, and new applications where electricity is locally
utilized may be a better fit, particularly for low efficiency BIPV systems.
Finally, Utterback and Afuah indicate: "if someone delivers form that helps the function
performance better it becomes a widely accepted design" (Utterback and Afuah 1998). It is
well known that there is a lot of energy around us that is not captured. If regulation
requires near-zero energy buildings, photovoltaic technologies will be options that will
allow us to capture energy close to the point of utilization.
However, BIPV systems are still in an early stage of development, and constructability
requirements should be validated and verified. In this context, it is still too soon to
anticipate what will be the dominant architectures, and whether BIPV fagade systems will
emerge as a widely adopted solution beyond niche markets. Principles of simplicity and
modularity will likely be leveraged by dominant architectures that elegantly take advantage
of the principles behind the behavior of energy in nature.
100
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